Production and application of on-grown Artemia in ...

Production and application of on-grown Artemia in freshwater ornamental fish farm LIAN CHUAN LIM1, ANDREW SOH2, PHILIPPE DHERT3 & PATRICK SORGELOOS3 1 Freshwater Fisheries Centre, Agri-food and Veterinary Authority of Singapore, Singapore 2 Associates Aquarium Pte Ltd, Singapore 3 Laboratory of Aquaculture & Artemia Reference Center, Ghent University, Gent, Belgium

Abstract This paper describes a pilot culture system for the production of on-grown Artemia in freshwater ornamental fish farms. The system had 21 culture units, each consisting essentially of three components: an oval-shaped raceway, an air-water lift system and two waste collectors. Using artificial seawater at 20 ppt for culture and at a mean production rate of 3 kg/m3 of water in a 12-day cycle, the system had a production capacity of 8 metric tons of on-grown Artemia a year. Biochemical analyses were preformed to evaluate the nutritional value of the on-grown Artemia against three conventional live feeds, viz. live Artemia nauplii, live Moina and frozen bloodworms. Cost-benefit analysis showed that with a capital investment of US$ 82,000 and an annual cost of production of US$ 81,000, the system achieved a high internal rate of return of 88% over a 10-year period and a short payback period of 1.23 years. The availability of on-grown Artemia would not only offer farmers and exporters a better alternative live food organism for feeding to their fish, but more importantly the possibility of enhancing the fish performance and quality through bioencapsulation. Keywords: on-grown Artemia, ornamental fish, Artemia production system, cost-benefit analyses Introduction The success in the hatchery production of fish fingerlings for stocking in the grow-out production systems is, to a large extent, dependent on the availability of suitable live food organisms for feeding to fish larvae, fry and fingerlings. In Singapore, the top-exporting country of freshwater ornamental fish in the world, Moina used to be the most common live food organism used in the industry. As Moina is cultured in ponds using pig waste (Shim 1988), they are often contaminated with fish pathogens, as well as bacteria of public health concern, such as Salmonella and Vibrio cholera. To minimize the risk of fish being contaminated with the pathogens, more and more freshwater ornamental fish farmers in Singapore have shifted from Moina to the cleaner Artemia nauplii for feeding their fish. . Correspondence L.C. Lim, Head, Freshwater Fisheries Centre, Agri-food and Veterinary Authority of Singapore, Lorong Chencharu, Singapore 769194, Republic of Singapore. Tel.: +65-7519850. Fax.: +65-7523242. E-mail: [email protected]

Aquaculture Economics and Management 5(3/4) 2001 211

mailto:[email protected]

212 Production of on-grown Artemia • L.C. Lim et al.

However, as Artemia nauplii (maximum length of instar-1 Artemia 0.55 mm) are only half the size of Moina (maximum length 1.20 mm), it is necessary to look for bigger organism to fill in the size gap. The bigger and older on-grown Artemia would be a good alternative live food for use in the hatchery.

Artemia nauplii, due to their convenience as an off-the-shelf food and requiring only 24 hours of incubation from cysts, are the most widely used live food organism for the fry production of marine as well as freshwater fish and crustaceans. Compared to Artemia nauplii, the use of the larger on-grown Artemia in the aquaculture industry is still not popular, because of the lack of supply. The objectives of this study are to develop a simple and cost-effective culture system for the production of on-grown Artemia suitable for operation in the freshwater ornamental fish farms, and to explore the possible applications of on-grown Artemia to enhance the performance and quality of the ornamental fish. Through this study we did not aim to develop a new Artemia rearing system, but to find a solution in balance with the production cost. The technology of Artemia culture reported in this study originated from Belgium and it was simplified and adapted to suit the conditions of local freshwater ornamental fish farms. The commercial production system is first of its kind in this region. A cost-benefit analysis was performed to study the economic feasibility of the system for use in freshwater ornamental fish farm in Singapore. Biochemical analyses were also conducted to evaluate the nutritional quality of the on-grown Artemia obtained from the system in comparison with three other common food organisms. Materials and methods Culture system of on-grown Artemia The pilot Artemia production system was set-up at a commercial ornamental fish farm located in the Lim Chu Kang Agrotechnology Park in Singapore. There were a total of 21 culture units in the system, occupying an area of 400 m2. Each unit consisted essentially of three components, the culture raceway, the air-water lift system and the waste collectors. The culture raceway was oval-shaped and made of concrete cement, with depth 1.2 m and total water capacity 5.6 m3 (Fig. 1). The middle of the raceway was fitted with a series of 18 pieces of air-water lift pumps to induce combined horizontal and vertical water current. This was to ensure proper aeration and adequate suspension of feed and Artemia in the culture water. Two waste collectors, one on each end of the tank, were placed in the raceway during the second week of the culture cycle. The waste collector consisted of a PVC frame (120 cm length x 15 cm dia.) covered with a removable screen (mesh 400 um) filled with expanded polystyrene (sponge) as filter media. An aeration collar fitted at the bottom of the collector served to reduce clogging of the filter mesh. The collectors were used as a mechanical filter to remove waste particles, such as fecal pellets, food wastes and exoskeletons of Artemia, from the culture tank. Water was driven continuously into the collector by an air-water lift pump connected to it and during the process, small waste particles passing through the nylon screen were trapped in the sponge filters inside the collector, while Artemia were retained in the raceway. The sponge filters in the waste collectors were cleaned on the alternate day.

Aquaculture Economics and Management 5(3/4) 2001 Partition

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L.C. Lim et al. • Production of on-grown Artemia 213

Fig. 1 Schematic views (not to scale) and dimensions (in cm) of culture system for the production of on-grown Artemia (above) and the waste collector (15 cm diameter) used in the system (below). Culture techniques of on-grown Artemia Artificial seawater instead of natural seawater was used in the culture. Preparation of artificial seawater was performed in the culture tank the day before inoculation of the Artemia nauplii. It was based on a modified formulation described in Dhont and Lavens (1996), but salinity of water was diluted to 20 ppt, which was 5 – 10 ppt lower than that of coastal water of Singapore. This was to cut down the cost of salts and to suit the conditions in the freshwater ornamental fish farms. The various salt ingredients were first dissolved in small volumes of water using an electric stirrer before addition into the culture tanks. Each raceway was inoculated with Instar-1 Artemia at 6,000/l of water. The Artemia nauplii were hatched from commercially available cysts of Great Salts Lake (GSL, Utah, USA) origin. Water temperature was not controlled and it followed the ambient temperature of the farm. The water temperature and salinity were measured with a handheld salinity, conductivity and temperature meter (YSI Model 30 M, YSI Incorporated, USA). Dissolved oxygen was determined with a dissolved oxygen meter (YSI Model 59, YSI Incorporated, USA), pH with a pocket-sized pH meter (Hanna Model pHep 2, Hanna Instruments, Portugal) and total ammonia with an ammonium test kit (Merck, Germany). To monitor the growth of Artemia, samples of the animal were collected from three culture tanks and fixed with Lugol's solution

Aquaculture Economics and Management 5(3/4) 2001


on every alternate day. The average length of 20 animals from each of the three tanks, measured from the top of the head to the base of the caudal furca using a dissecting microscope equipped with a drawing mirror, was determined and their mean and standard deviation calculated. At the end of the culture cycle, another set of samples (about one gram each) of the Artemia was collected and weight and number of animals in each sample were determined for computation of the mean and standard deviation of the individual weight of the Artemia. The data were used for estimation of the survival rate of Artemia in the culture tanks.

Artemia were fed a specially prepared feed consisting of two-third of rice bran and one-third of de-fat soybeans. The feed ingredients were first mixed with water using an electric stirrer and the food suspension was then distributed evenly throughout the raceway. Feeding started from the next day after inoculation. The food density in the culture water was adjusted according to the age and size of the Artemia. A turbidity-stick for checking the transparency of the water was used to determine whether the food density was sufficient for the Artemia, following the method described by Lavens et al. (1986). The Artemia were fed at regular intervals so as to maintain the transparency of the culture water at 15 – 20 cm during the first week and 20 –25 cm during the remaining period. The culture cycle took 12 days. During the process, the conditions of the Artemia were examined daily under a microscope to ensure that the digestive tracts of the animals were filled with feed. There was no renewal of water throughout the 12-day culture cycle.

Artemia were harvested taking the advantage of the surface respiration of the animals. Before harvesting, aeration was switched off and after half an hour, the Artemia accumulated on the surface water were scooped off with a net. The harvested Artemia were washed thoroughly with freshwater and weighed using a top-pan balance. They were packed at 30 g per bag in a plastic bag with 500 ml each of seawater and oxygen for transport and sale to other fish farms or aquarium shops. The average yield of on-grown Artemia was calculated using records from three culture cycles, each with 20 tanks. Nutritional analyses of food organisms To evaluate the nutritional quality, on-grown Artemia were analyzed for proximate composition, amino acids and fatty acids. For purpose of comparison, samples of the common food organisms used in aquaculture, such as Artemia nauplii, Moina micrura and bloodworms (midge larvae, family Chironomidae) were also analyzed. On-grown Artemia used in the analyses were harvested from the culture system. Artemia nauplii were hatched from the same batch of cysts (GSL, Utah, USA) used for culture of the on-grown Artemia. Moina were obtained from commercial culture in ponds enriched with pig dung and bloodworms were imported in frozen form from Indonesia. Fatty Acid Methyl Ester (FAME) analyses were performed following the method modified from Lepage and Roy (1984) (Coutteau & Sorgeloos 1995). Proximate analyses and amino acids were conducted using the methods described in Egan et al. (1981) and Anonymous (1990) respectively. Bioencapsulation of Artemia An observation was conducted to look into the application of a bioencapsulation technique to enhance the (n-3) highly unsaturated fatty acids (HUFA) content in the on-grown Artemia. The animals were enriched with an oil emulsified product rich in docosahexaenoic acid or DHA (DHA-Selco, supplied by INVE Aquaculture, Belgium) at a dosage of 0.6 g/l. Samples were collected before and after bioencapsulation and stored at –80oC in an ultra-low freezer until they were analyzed for fatty acids. Economic and financial analyses



Economic and financial analyses were performed to study the economic viability of the system. Straight-line method was used to allocate the cost of fixed assets through depreciation, with the depreciable cost of the asset spread over the life of the asset. The cost of capital was set at 7.5%, which was 2% above prime lending rates of 5.5%, as commonly practiced by the major banks in Singapore. For purpose of discounted cash flow analyses, net cash flow excluding interest charge on initial capital was used in the calculation of the internal rate of return (IRR) and net present value (NPV), because the discounting process itself was allowing for the interest on capital. The payback period was calculated with allowance for interest costs on the outstanding balance by calculating the NPV of each year’s net cash flow and cumulative total of these annual NPVs, with the point at which this became positive being the payback period.

In late1999, the farm where the pilot system was located obtained approval from its neighboring National Park to draw seawater from the coastal area off the Park for use in the Artemia culture. The culture was therefore shifted to the use of natural seawater to save the cost of salts for preparation of artificial seawater. The natural seawater was diluted to 20 ppt for use in culture. The change provided an opportunity to perform a cost-benefit analysis of the system using natural seawater, which was applicable to farms located near the coast where seawater was readily available. Further analyses were conducted to test the sensitivities of the performance of the culture system to lower sale prices and to lower production rates. A number of sale prices ranging from the unit cost of production to the existing sale price of US$ 20/kg, and production rates ranging from 1.2 kg/m3 (40% of existing rate) to the existing rate of 3 kg/m3, were used in these analyses respectively. Results Production yield and growth of on-grown Artemia The average yield of on-grown Artemia, after a 12-day culture at salinity 20 ppt, varied from 15.1 to 19.58 kg/tank per run , with mean 16.81 ± 1.65 kg/tank. The average production rates ranged from 2.70 to 3.50 kg/m3 per run, with mean 3.03 ± 0.28 kg/m3. During the culture cycle, the diurnal water temperatures fluctuated within the range of 25 - 30 oC, pH 7.5 – 8.0 and dissolved oxygen more than 4 mg/l. The total ammonia and free ammonia were below 45 mg/l and 3.5 mg/l respectively. Fig. 2 shows the growth curve of the Artemia during the 12-day culture cycle. At stocking density of 6,000 nauplii per liter of water, the Artemia grew from 0.45 mm to about 5 mm in length during the period. The mean individual weight of on-grown Artemia at the time of harvesting was 2.89 ± 0.05 mg. Hence with the mean production rate of 3.03 kg/m3, the average survival rate was estimated to be around 17.5%.



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Fig. 2 Growth pattern of Artemia during the 12-day culture cycle. Vertical bar indicates the standard deviation. Nutritional quality Table 1 compares the proximate composition of on-grown Artemia with Artemia nauplii, Moina and bloodworms. Although there were marked differences in the proximate compositions, protein was the major organic constituent in all the four food organisms. The protein content in percentage of dry matter in on-grown Artemia was quite high, about 67%, which was 5% and 21% higher than those recorded in Artemia nauplii and bloodworms respectively, but 11% lower than that in Moina. On the other hand, the crude fat in on-grown Artemia was only 4%, which was about the same level as bloodworms, but only half of that recorded in Moina and slightly more than one-quarter of that in Artemia nauplii. Table 1 Proximate composition of on-grown Artemia and three common natural feeds used in ornamental fish production. Results expressed in % dry weight.

Component On-grown Artemia Artemia nauplii Moina Bloodworms

Crude protein 67.40 61.88 78.63 46.33 Carbohydrate 10.80 10.56 0.78 30.24 Crude fat 4.00 14.44 7.65 3.20 Crude fiber 4.20 6.75 5.88 4.14 Ash 13.60 6.38 7.06 16.09

The amino acid profiles of on-grown Artemia, Artemia nauplii, bloodworms and Moina

are shown in Table 2. The results revealed that all the ten essential amino acids were present in sufficient quantity in all the four types of food organisms. Both the amounts of total amino acids and total essential amino acids of the on-grown Artemia were at about the same levels as in Moina, but higher than those in the Artemia nauplii and bloodworms.



Table 2 Amino acid profiles (mg/g dry weight) of on-grown Artemia and three common natural feeds used in ornamental fish production.

Amino acids On-grown Artemia

GSL Artemia nauplii

Blood-worms Moina

Essential amino acids Lysine 40 29.6 30.5 43.1 Histidine 16 4.0 14.1 15.7 Arginine 62 40.5 28.1 51.0 Threonine 34 24.7 25.8 33.3 Valine 32 29.5 32.8 37.3 Methionine 16 15.9 21.9 19.6 Isoleucine 24 17.6 25.0 25.5 Leucine 50 36.6 42.2 51.0 Tyrosine 30 25.6 20.3 33.3 Phenylalanine 34 32.6 38.3 35.3 Total essential amino acids 338 (53.3%) 256 (52.9%) 279 (56.7%) 345 (52.1%)

Non-essential amino acids Aspartic acid 60 48.0 57.8 58.8 Serine 32 32.6 28.1 29.4 Glutamic acid 84 62.6 47.7 80.4 Proline 34 24.2 14.1 51.0 Glycine 28 25.1 21.1 29.4 Alanine 42 26.4 37.5 51.0 Cysteine 16 8.4 6.3 17.6

Total non-essential amino acids 296 (46.7%) 227 (47.1%) 213 (43.3%) 317 (47.9%)

Total amino acids 634 483 492 662

Table 3 compares the lipid profiles of on-grown Artemia, Artemia nauplii, Moina and bloodworms. The total amount of fatty acid, expressed in total FAME, was almost 50 mg/g dry weight (DW) in on-grown Artemia, which was at a similar level as that in Artemia nauplii, but was about 70% and 60% of those in Moina and bloodworms respectively. The total (n-3) polyunsaturated fatty acids (PUFA) in on-grown Artemia was very low (4.5 mg/g DW), being only 26%, 37% and 44% of those recorded in Artemia nauplii, Moina and bloodworms respectively. This was due to the extremely low 18:3(n-3) (linolenic acid or LNA) recorded in on-grown Artemia (1.7 mg/g DW), which was only 13% - 24% of the levels found in the other three food organisms. In contrast, the total (n-3) HUFA in the on-grown Artemia was the highest among the four food organisms (2.7 mg/g DW), being 35% higher than that of Artemia nauplii, and more than double of that in Moina and bloodworms. The two most important essential fatty acids, 20:5(n-3) (eicosapentaenoic acid or EPA) and 22:6(n-3) (docosahexaenoic acid or DHA) in the on-grown Artemia were also higher than the corresponding values recorded in the other three food organisms. Furthermore, the long chain (n-6) PUFA in the on-grown Artemia, including the total (n-6) HUFA, 18:2(n-6) (linoleic acid or LLA) and 20:4(n-6) (arachidonic acid or ADA), were again the highest among the four food organisms tested.



Table 3 Fatty acid profiles of on-grown Artemia and three common natural feeds used in ornamental fish production. Results are in terms of mg/g dry weight.

Fatty acids On-grown Artemia Artemia nauplii Moina Bloodworms

14:0 0.3 0.3 1.3 2.0 15:0 0.3 0.2 1.0 0.5 16:0 3.9 4.1 10.5 14.4 17:0 1.0 0.3 1.1 1.1 18:0 3.9 3.4 3.3 5.8 19:0 0.1 0.0 0.1 0.2 20:0 0.1 0.1 0.1 0.2 22:0 0.4 0.5 0.5 0.2 24:0 0.1 0.1 0.2 0.1 Total saturates 10.1 8.9 18.1 24.5

14:1(n-5) 0.4 0.8 0.8 0.6 15:1(n-5) 0.1 0.1 0.5 0.2 16:1(n-7) 1.7 1.2 11.2 3.1 17:1(n-7) 0.1 0.0 0.2 0.1 18:1(n-9) 7.4 7.2 5.1 6.5 18:1(n-7) 6.1 3.9 6.8 2.3 19:1(n-9) 0.2 0.3 0.2 0.1 20:1(n-9) 0.2 0.3 0 0 20:1(n-7) 0.1 0 0 0 22:1(n-9) 0.1 0.1 0 0 23:1(n-9) 0 0.1 0 0

Total monoenes 16.4 14.0 24.8 12.9

18:2(n-6) LLA 15.4 2.9 9.4 8.1 18:3(n-6) 0.2 0.4 0.3 1.0 20:3(n-6) 0.1 0.1 0.1 0.1 20:4(n-6) ADA 1.8 1.0 0.8 0.7 22:5(n-6) 0 0.1 0 0 Total (n-6)PUFA 17.5 4.5 10.6 9.9 Total (n-6)HUFA 1.9 1.1 0.9 0.8

18:3(n-3) LNA 1.7 12.9 10.7 7.1 18:4(n-3) 0.2 2.1 0.3 2.0 20:3(n-3) 0.1 0.4 0.1 0 20:4(n-3) 0 0.3 0.1 0.1 20:5(n-3) EPA 1.7 0.9 1.0 0.9 22:5(n-3) 0 0.1 0 0 22:6(n-3) DHA 0.8 0.3 0.1 0.1 Total (n-3)PUFA 4.5 17.0 12.3 10.2 Total (n-3)HUFA 2.7 2.0 1.3 1.1

DHA/EPA ratio 0.47 0.35 0.10 0.11 (n-6)/(n-3) 3.89 0.26 0.86 0.97 Total mg FAME/g DW 49.50 47.50 72.30 62.40 %DW 5.80 12.10 6.14 12.77

PUFA: polyunsaturated fatty acids; HUFA: highly unsaturated fatty acids (containing 20 C or more); FAME : Fatty acid methyl ester. Fatty acids were determined from a single pooled sample



Bioencapsulation of on-grown Artemia Microscopic examination showed that before bioencapsulation, the digestive tracts of the on-grown Artemia were either filled with food particles or fecal materials. When the Artemia were subjected to bioencapsulation, they began to ingest the oil emulsified product and had their digestive tracts partially filled with pink oil particles. By three hours after bioencapsulation, majority of the digestive tracts of the on-grown Artemia have turned pink, indicating the completion of bioencapsulation.

Fig. 3 compares the essential fatty acids profile of the on-grown Artemia before and after bioencapsulation. While there was no change in the LNA, the EPA and DHA increased by 224% and 125% respectively after bioencapsulation for three hours. There was also marked increase in the total (n-3) HUFA, from 2.7 mg/g to 7.8 mg/g, or by 188%, after the enrichment period.

0

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FA (m

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Fig. 3 HUFA levels in on-grown Artemia before (0 hour) and after (3 hours) bioencapsulation using oil emulsified product rich in DHA. Abbreviations of essential fatty acid are LNA: linolenic acid, 18:3 (n-3); EPA: eicosapentaenoic acid, 20:5 (n-3); DHA: docosahexaenoic acid 22:6 (n-3). Economic and financial analyses The system required only a small land area of 0.04 ha, and produced 8 metric ton of on-grown Artemia a year. Estimation of the production capacity was based on the mean production rate of 3 kg/m3 of water per cycle, 16.8 kg/unit/cycle (3 kg/m3 x 5.6 m3) and 336 kg per run for the whole system (16.8 kg/unit x 20 unit, with one unit as standby). As each culture cycle took only about 12 days, it was assumed that the culture system could operate at least two runs a month or 24 runs a year.

The estimated total capital investment required to run the culture system was about US$ 82,000 (Table 4), majority of which (97%) was spent on investment on fixed asset and the rest (3%) on working capital. For system using artificial seawater, the estimated total annual cost of production was US$ 81,100, which consisted of 19% fixed costs and 81% variable costs (Table 5). The fixed costs consisted mainly of depreciation of fixed assets and cost of capital, which accounted for 11 % and 8% of the total annual cost of production respectively. Among the various components of variable costs, the two most expensive items were salts for preparation of artificial seawater (31%) and staff salary (24%). The two other major variable costs were electricity and water and Artemia cysts (9% each). Marketing cost was not provided as it consisted mainly of the manpower cost of the supervisor, which has been taken



care of in staff salary. There was also no storage cost as the on-grown Artemia were sold when they were ready for the market. Table 4 Estimated capital investment of an Artemia culture system with production capacity of 8 m. ton/year

Artificial seawater Natural seawater

Cost Items

Life expectancy (years)

Initial cost (US$)

Depreciated annual cost

(US$)

Initial cost (US$)

Depreciated annual cost

(US$) I. Fixed assets 79,233 (96.7%) 8,609 83,433 (98.1%) 9,009 1. Culture shed

Land development & flooring 10 2,400 240 2,400 240 Shed 10 2,400 240 2,400 240

2. Culture system

Culture raceway (5.6 m3) 10 15,750 1,575 15,750 1,575 @ US$750 x 21 Air-water lift pumps 10 1,260 126 1,260 126 @ US$ 60 x 21 sets Waste collectors 10 2,520 252 2,520 252 @ US$ 60 x 42 pcs

3. Support system

Air blower (11 kw) 5 4,550 910 4,550 910 Air distribution system 10 600 60 600 60 Drainage system 10 1,200 120 1,200 120 Seawater intake system 10 - - 3,000 300 Filtration systems 10 - - 1,000 100

4. Water testing equipment Oxygen meter 5 1,800 360 1,800 360 pH tester 2 60 30 60 30 Salinity refractometer 5 180 36 180 36

Turbidity-stick 2 20 10 20 10 Stereo-microscope 10 1,100 110 1,100 110 5. Other equipment

Water delivery pump (1 kw) 3 720 240 720 240 @ US$ 360 x 2 Water pressure jet 3 900 300 900 300 Feed micronized machine 10 40,000 4,000 40,000 4,000

6. Contingency 3,773 3,973

Total cost (1-5) x 5% II. Working capital 2,746 (3.3%) 1,618 (1.9%)

(Total variable cost / 24 runs) III. Total capital investment [(I) + (II)] 81,979 85,051



Table 5 Estimated annual cost of production of 8 m. ton of on-grown Artemia

Artificial seawater Natural seawater

Cost Items

Cost (US$) Percentage of total cost (%)

Cost (US$) Percentage of total cost (%)

I Fixed costs 15,217 18.8 15,848 29.0 1. Depreciation 8,609 10.6 9,009 16.5 2. Cost of capital 6,148 7.6 6,379 11.7 (Total capital x 10% interest) 3. Land cost @ US$ 10,000/ha x 0.04 ha 400 0.5 400 0.7 4. Property tax Land rental x 15% 60 0.1 60 0.1 II. Variable costs 65,911 81.2 38,821 71.0 1. Artemia cysts 7,056 8.7 7,056 12.9 @4.2 kg/run x US$ 70/kg x 24 run 2. Feeds 2,016 2.5 2,016 3.7 @ 700 kg/run x US$ 0.12/kg x 24 run 3. Electricity & water 7,200 8.9 6,000 11.0 @ US$ 600/mth x 12 mth 4. Salts 25,200 31.1 0 0.0 @ US$ 1,050/run x 24 run 5. Staff salary 19,500 24.0 19,500 35.7 Supervisor US$ 6,500 (@ US$ 2,500/mth x 13 mth x 20%) Worker US$ 13,000 (@ US$ 1,000/mth x 13 mth ) 6. Other supplies and materials 1,200 1.5 1,200 2.2 e.g. plastic bag, oxygen, plankton netting materials, etc. @ US$100/mth x 12 mth 7. Maintenance of equipment 600 0.7 1,200 2.2 8. Contingency 3,139 3.9 1,849 3.4 Total cost (1-7) x 5% III. Total annual cost of production [(I) + (II)] 81,128 54,668

A cost-benefit analysis of the operation of the Artemia culture system was given in Table 6. To produce 8 metric tons of on-grown Artemia a year using artificial seawater, the total annual production cost was US$ 81,100 and the unit cost of production was US$ 10.14/kg. Based on the current ex-farm price of US$ 20.00/kg, the annual return from 8 metric ton of on-grown Artemia was US$ 160,000. The return almost doubled the investment, with US$ 1.97 per $ investment. The payback period was only 1.23 years. The IRR over a 10-year period was as high as 88%. Table 6 Cost-benefit analyses of an Artemia production system with production capacity of 8 m. tons a year



Items Artificial seawater Natural seawater 1 Total annual cost of production (US$) 81,128 54,668 2. Annual yield (kg) 8,000 8,000 3. Cost of production (US$/kg Artemia) [(1) / (2)] 10.14 6.83 4. Sale price (US$/kg) 20.00 20.00 5. Annual returns (US$) [(2) x (4)] 160,000 160,000 6. Return per $ investment (US$) [(4)/(3)] 1.97 2.93 7. Taxable income (US$) [(5) - (1)] 78,872 105,332 8. Depreciation (US$) 8,609 9,009 9. Total annual cost of production less

depreciation (US$) [(1) - (8)] 72,519 45,659

10. Gross cash return (US$) [(5) - (9)] 87,481 114,341 11. Income tax (US$) [(7) x 27%] 21,295 28,440 12. Gross cash return less income tax [(10) - (11)] 66,186 85,901 13. Total capital investment (US$) 81,979 85,051 14. Interest (US$) [(13) x 7.5%] 6,148 6,379 15. Net cash flow (US$) excluding interest

[(12) + (14)] 72,334 92,280

16. Net present value (US$) [based on (15) @7.5% interest, 10 years]

414,527 548,366

17. Internal rate of return (%) [based on (15) @ 10 years]

88.08 108.43

18. Payback period (year) 1.23 0.99

When natural seawater was used for culture, there were savings in the costs of salts (US$ 25,200) for preparation of seawater and water (US$ 1,200). The additional costs include the fixed cost for setting up a seawater intake system (US$ 3,000) and a filtration system (US $ 1,000) (Table 4), and the variable cost for maintenance of the intake system (US$ 600) (Table 5). There was no noticeable difference in the performance of the on-grown Artemia when the culture was shifted to natural seawater. Fig. 4 shows that at the existing sale price of US$ 20/kg, the IRR increased to 108% and the payback period reduced to one year when natural seawater was used for production. It also demonstrated that the present system using artificial seawater would still remain commercially viable if the sale price was reduced to US$ 13.30/kg, at which the IRR was 40% and the payback period 2.8 years. The same could be achieved at the sale price of US$ 10.20/kg when natural seawater was used.



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Fig. 4 Effects of changes in sale price on the Internal Rate of Return (IRR) and payback period. Abbreviations of seawater are Nat. SW: Natural seawater (25 ppt), Art. SW: Artificial seawater (20 ppt).

Fig. 5 shows that at the sale price of US$ 20/kg, the system using artificial seawater for culture would still remain viable even if the production dropped to two-third of the existing rate (2 kg/m3). The IRR over a 10-year period and the payback period were 40% and 2.8 years respectively. When the culture shifted to using natural seawater, almost the same return (39%, 2.9 years) could be achieved even if the production rate dropped further to 50% of the existing level (1.5 kg/m3).

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Fig. 5 Effects of changes in production rate on the Internal Rate of Return (IRR) and payback period. Abbreviations of seawater are Nat. SW: Natural seawater (25 ppt), Art. SW: Artificial seawater (20 ppt).



Discussion The Artemia culture system reported in this paper was designed for operation in the freshwater ornamental fish farms. The pilot system with an annual production capacity of 8 metric ton required only a land area of 0.04 ha, which was merely 2% of the total land area of a standard 2-ha ornamental fish farm in Singapore. The ornamental fish farmers would have no problem to assign such a small area for setting up the culture system in their farms. While the use of a batch culture system instead of a flow-through system would cut down the volume of seawater required for Artemia culture, the use of artificial seawater would enable farms that have no access to seawater to operate the system. To cut down the cost of salts required for preparation of artificial seawater, the present system, for the first time in commercial Artemia production, used diluted artificial seawater (salinity 20 ppt) instead of full strength seawater for the culture. Change of water was not necessary during the 12-day culture period. These characteristics made the system suitable for operation in freshwater ornamental fish farms, and would allow existing ornamental fish farmers to integrate the Artemia production system in their farm operation.

The present system did not use expensive mechanical and biological water treatment equipment such as bio-filter, mechanical filter, plate separator, sensors etc. and hence the cost of setting up the system was US$ 82,000 only. It was only a fraction of the sophisticated commercial systems used in Europe, which cost at least half a million dollars each to set up and operate. The working capital was US$ 2,746 only. Bioencapsulation to enhance the nutritional quality of on-grown Artemia was conducted only when the Artemia failed to meet the fish requirement. The same applied to all other live food organisms such as rotifers and Artemia nauplii which might also require bioencapsulation due to their nutritional deficiency (Leger & Sorgeloos 1992; Sorgeloos & Leger 1992; Sorgeloos et al. 1995). It was performed by fish farmers just before feeding the Artemia to fish, and not by producer of the organism. Hence the cost of bioencapsulation was not included in the production cost of the Artemia. Nevertheless, the cost of the enrichment media (US$ 70/kg) used in bioencapsulation was estimated to be US$ 2/kg of on-grown Artemia (in 50 liter of water at 0.6 g/l). Unlike the complex, cost-intensive automation system used in Europe, which required skilled personnel to manage, the present system was simple and easy to operate, and required minimal technical expertise. The manpower cost to operate the pilot system was very low (US$ 19,500), as it required only a worker to operate, and occasional supervision and auditing of the production procedure by the manager or farm supervisor. These characteristics made the system more affordable to the freshwater ornamental fish farms. The on-grown Artemia harvested from the system could be used for feeding to their fish, as well as for sale to other farms or pet fish shops to increase farm profitability.

With the pilot system, the cost of production of on-grown Artemia was US$ 10.14/kg using artificial seawater and US$ 6.83/kg using natural seawater. Both values were within the range of US$ 2.50 to 12/kg obtained in super-intensive Artemia farms in USA, France, UK and Australia (Dhont & Lavens 1996). The use of on-grown Artemia was more affordable for the Singapore fish farmers, as the wholesale price in Singapore was only US$ 20/kg, which was much lower than US$ 25 – 100/kg in other countries. Despite of the low sale price, the system was still highly profitable. Due to its low investment cost, the system had a high IRR over a 10-year period and a short payback period, being 88% and 1.23 years respectively when using artificial seawater and 108% and 0.99 years respectively when using natural seawater.

In practice, farmers may be forced to lower their sale prices due to factors like new competitors entering into the market, over-production of on-grown Artemia, or lowering of



sale prices of other live feeds. Our study showed that the system would remain commercially viable if the sale price dropped to US$ 13.30/kg for culture using artificial seawater and to US$ 10.20/kg for farm having access to natural seawater. On the other hand, the production rate may also be lowered as full-scale commercial performance may often be somewhat poorer than in a pilot project, and there may be risks of disease or other factors, which could result in loss of a complete batch occasionally. Again, our analyses suggested that the system would still be profitable if the production reduced to 2 kg/m3 in culture using artificial seawater or further down to 1.5 kg/m3 in culture using natural seawater. In all the above four cases, the IRR were close to 40% and payback periods less than 3 years. These results demonstrated that the commercial production of on-grown Artemia using the present culture system was highly viable for freshwater ornamental fish farms.

Dhont and Lavens (1996) summarized the performance data of the different culture systems for on-grown Artemia, which allowed comparison of the performance of the present systems with other known systems. The production rate of on-grown Artemia obtained from the present system after 12-day culture was 3 kg/m3, which was lower than the average yield of 5 kg/m3 after two-week culture obtained from batch production. The lower production rate obtained in this study was the result of low survival rate, which was only 17.3%, as compared to 29 – 59% obtained from cultures using GSL Artemia cysts. The water quality parameters of the present system, such as pH (7.5 – 8), dissolved oxygen (more than 4 mg/l) and total ammonia content (less than 45 mg/l), were all within the tolerance levels of 6.5 – 8, 2.5 mg/l and 1,000 mg/l respectively (Dhont & Lavens 1996). Although using more complicated systems to improve the water quality may enhance the performance of on-grown Artemia, this would make the system less affordable to farmers. On the other hand, the water temperatures (25 – 30 oC) of the system were outside the optimal range of 19 – 25 oC. The high temperature and low salinity used in the present system might have contributed to the low survival rate of the on-grown Artemia.

The present Artemia culture system was more profitable, less labor intensive and more effective than the Moina culture system in Singapore reported by Shim (1988). Moina were cultured in earthen ponds using wastewater from pig farms as fertilizers, and its average production rate was 140 g/wk/m3, which was equivalent to 7.3 kg/m3/year. This figure was only 10% of the production rate of on-grown Artemia (3 kg/m3 x 24 run/year = 72 kg/m3/year) obtained in the present study. A Moina farm with a farm area of 2 ha required five workers to operate and its annual revenue was US$ 24,000 only. With only 2% of the size of Moina farm and one worker to operate, the present Artemia production system had an annual gross cash return (after tax) ranging from US$ 66,200 (artificial seawater culture) to US$ 85,900 (natural seawater culture). These values were 2.5 – 3.6 times of that obtained from Moina culture. The higher return obtained from the Artemia culture system was partly due to the higher sale price of the Artemia, being US$ 20/kg compared to only US$ 3.60/kg in Moina. Due to the severe handling stress during the harvesting operation, the survival of Moina was less than 40% on arrival at the ornamental fish farm. The problem of pathogen contamination in Moina arising from the use of pig manure for culture also led to many ornamental fish farmers in Singapore shifting from Moina to Artemia nauplii or juveniles for feeding their fish. Apparently, the higher price of on-grown Artemia was sustained by the high demand for the organism. In the aquarium fish shops in Singapore, on-grown Artemia was sold at US$ 40/kg (US$ 1.20/30g), which was only one-third higher than Moina at US$ 30/kg (US$ 0.60/20 g). The small price difference between the two organisms suggested that there was good potential for on-grown Artemia in the hobbyists’ market.

The food value of a live food organism for a particular fish species was primarily determined by its size and form. While a small food organism was desirable for fish larvae in



term of ingestibility, the use of larger organisms was more beneficial as long as the size of the food organism did not interfere with the ingestion mechanism of the predator (Merchie 1996). Fish would take a long time to attain satiation if fed with smaller live food organism, and this would result in poor growth due to inefficient feeding and waste of energy. The on-grown Artemia in the culture system grew from 0.45 mm at inoculation to an average length of about 5 mm in 12 days. This size range was considered suitable for all sizes of freshwater ornamental fish species of up to 10 cm total length. By varying the harvesting time during the 12-day cycle, it was possible to obtain Artemia of any specific size within the size range for feeding, which would ensure a better energy balance in food uptake and assimilation. The flexibility in tailoring the prey size according to the age and size of the fish to be fed was limited with other smaller live food organisms such as rotifers and Moina.

Our results showed that the nutritional quality of on-grown Artemia was comparable or superior to the common food organisms being used by the freshwater ornamental fish industry, such as Artemia nauplii, Moina and bloodworms. The on-grown Artemia was rich in protein (67%) and low in crude fat (4%). It was reported to have superior nutritional digestibility and a thin exoskeleton rich in essential amino acids (Leger et al. 1986). The latter was consistent with our amino acids analyses, which showed that the essential amino acids in the on-grown Artemia were comparable to Moina and richer than Artemia nauplii and bloodworms. An important dietary characteristic of live food organism was its composition of essential fatty acids. Watanabe (1987) reviewed the essential fatty acid requirement of freshwater and marine fish and concluded that freshwater species required mainly LLA or LNA or both. Although the on-grown Artemia obtained from the present study was deficient in LNA, its LLA was the highest among all the four diets tested. The DHA and EPA, which were widely considered as essential for marine organisms (Kanazawa et al. 1979), were also highest in on-grown Artemia. Due to lack of published data, it was not known whether the levels of LLA, LNA, EPA and DHA in food organisms would be important to freshwater ornamental fish. However, recent evidences suggested that freshwater species might also have the fatty acid requirements of marine fish (Watanabe 1987; Merchie 1996). Research in how these essential fatty acids would affect the performance of the freshwater ornamental fish would be needed. On the other hand, we found that ADA and total (n-6) HUFA in the on-grown Artemia were also higher than the other three food organisms. ADA might be essential to the maturation and spawning of freshwater ornamental fish. Recent study on the fatty acid profiles of common feed items used by the industry for maturation such as beef heart and tubifex worms found unusually high ADA levels (Ako et al. 1999). Tamaru et al. (2000) reported that both the ADA/EPA ratio and the ADA/total fatty acids ratio in the broodstock diet of armored catfish (Corydoras aeneus) were directly correlated with the egg production (No./spawn) of the fish. ADA has also been shown to participate in gonadotropin-releasing hormone stimulation of gonadotropin in goldfish (Chang et al. 1989).

Our study demonstrated that the nutritional quality of on-grown Artemia in term of HUFA content could be enhanced through bioencapsulation. Artemia, being a continuous, non-selective filter feeder, was able to ingest any food particles smaller than its mouth size. With the bioencapsulation technique, the nutritional quality could be tailored to suit the fish requirement. The technique would have important applications in improving the performance and enhancing the quality of ornamental fish. Due to the small size of the brooders of ornamental fish, which are less than 100 g in most species, the enriched on-grown Artemia may also be used to enhance the nutritional quality of the broodstock. Hence, the possible applications include boosting the on-grown Artemia with (a) essential nutrients such as (n-3) HUFA to improve growth and survival, reduce incidence of deformity and increase vigor, (b)



pigments or color enhancer to obtain better color or pigmentation, (c) appropriate hormone to induce sex reversal, maturation, and spawning, (d) therapeutic drugs for fish disease treatment and (e) vaccine for fish immunization. In addition, bioencapsulated Artemia may also be used for nutritional prophylaxis, that is, to enhance the stress resistance and disease resistance of ornamental fish by incorporating products such as vitamin C or immuno-stimulants in the on-grown Artemia for fish feeding. This is likely to lead to improvement in post-shipment survival. Availability of the on-grown Artemia would offer our farmers and exporters the possibility to apply the bioencapsulation technique to improve their fish performance and quality. In addition, the effective bioencapsulation characteristics of on-grown Artemia also make the organism a useful tool for larval nutrition study on freshwater ornamental fish. Conclusion The present Artemia culture system is a cheap alternative to the more sophisticated super-intensive system used in Europe. Compared to the complex automated system, the present system is cost effective, simple and easy to set up and operate. As the system occupies only a small land area and uses diluted artificial seawater for culture, the freshwater ornamental farmers will have no problem to integrate Artemia production using the culture system into their farm operation to increase farm profitability. By varying the time of harvesting, farmers may harvest any specific size of on-grown Artemia of up to 5 mm from the culture system to suit the age and size of their fish. The use of the right size of on-grown Artemia for feeding would ensure a better energy balance in food uptake and assimilation, thereby improving the performance of the fish. These characteristics, coupled with the use of bioencapsulation technique to enhance the quality of the on-grown Artemia, would make the organism an ideal nursery diet for freshwater ornamental fish. The availability of on-grown Artemia and the application of bioencapsulation techniques using the organism are likely to have a positive impact to the ornamental fish industry. Acknowledgements This Artemia study was supported by the Singapore National Science and Technology Board under the project NSTB 16/4/21: Development of Water Re-circulation System for Farming Discus. The first author would like to thank his colleagues in the Agri-food and Veterinary Authority of Singapore, in particular, Ms Serena Cho, Mr Wong Chee Chye, Ms Lim Seok Keew and Mdm Ang Siew Lan for their technical assistance during the conduct of the study, and Mr Liew Wai Keat, Research Assistant for the project, for maintaining the culture system. References Ako, H., Tamaru, C. & Asano, L. (1999) Colour, maturation, and palatability feeds. In:

Conference Abstracts, AQUARAMA ’99 World Conference on Ornamental Fish Aquaculture, 3-6 June 1999, pp. 43. Miller Freeman, Singapore.

Anonymous (1990) Hewlett Packard AminoQuant Series II Operator’s Handbook. Hewlett-Packard, Germany.



Chang, J. P., Freedman, G. L. & Leeuw, R. (1989) Participation of arachidonic acid metabolism in gonadotropin-releasing hormone stimulation of goldfish gonadotropin release. General and Comparative Endocrinology, 76, 2-11.

Coutteau, P. & Sorgeloos, P. (1995) Intercalibration exercise on the qualitative and quantitative analysis of fatty acids in Artemia and marine samples used in mariculture. International Council for the Exploration of the Sea Cooperative Research Report, No. 211.

Dhont, J. & Lavens, P. (1996) Tank production and use of on-grown Artemia. In: Manual on the Production and Use of Live Food for Aquaculture (eds P. Lavens & P. Sorgeloos), pp. 164-195. FAO Fisheries Technical Paper 361, FAO, Rome.

Egan, H., Kirk, R.S. & Sawyer, R. (1981) Pearson’s Chemical Analysis of Foods. 8th edition, Churchill Livingstone, Edinburgh.

Kanazawa, A., Teshima, S.I. & Ono, K. (1979) Relationship between fatty acid requirements of aquatic animals and the capacity for bioconversion of linolenic acid to highly unsaturated fatty acids. Comparative Biochemistry and Physiology, 63B, 295-298.

Lavens, P., Baert, P., De Meulemeester, A., Van Ballaer, E. & Sorgeloos, P. (1986) New developments in the high density flow-through culturing of brine shrimp Artemia. Journal of World Aquaculture Society, 16, 498-508.

Leger, P., Bengtson, D.A., Simpson, K.L. & Sorgeloos, P. (1986) The use and nutritional value of Artemia as a food source. Oceanographic Marine Biology Annual Review, 24, 521-623.

Lepage, G. & Roy, C.C. (1984) Improved recovery of fatty acid through direct transesterification without prior extraction or purification. Journal of Lipid Research, 25, 1391-1396.

Leger, P. & Sorgeloos, P. (1992) Optimized feeding regimes in shrimp hatcheries. In: Marine Shrimp Culture: Principles and Practices (eds Fast A. W. & J. Lester), pp. 225-244. Elsevier Science Publishers.

Merchie, G. (1996) Use of nauplii and meta-nauplii. In: Manual on the Production and Use of Live Food for Aquaculture (eds P. Lavens & P. Sorgeloos), pp. 137-163. FAO Fisheries Technical Paper 361, FAO, Rome.

Shim, K.F. (1988) Mass production of Moina in Singapore using pig waste. World Aquaculture, 19(3), 59-60.

Sorgeloos, P., Dehasque, M., Dhert, P. & Lavens, P. (1995) Review of some aspects of marine fish larviculture. International Council for the Exploration of the Sea Marine Scientific Symposium, 201, 138-142.

Sorgeloos, P. & Leger, P. (1992) Improved larviculture outputs of marine fish, shrimp and prawn. Journal of the World Aquaculture Society, 23(4), 251-164.

Tamaru, C.S., Pang, L. & Ako, H. (2000) Effects of three maturation diets on spawning of the armored catfish (Corydoras aeneus). Aquatips, Regional Notes. Center for Tropical and Subtropical Aquaculture, 11(3), 4-6.

Watanabe, T. (1987) The use of Artemia in fish and crustacean farming in Japan. In: Artemia Research and its Applications. Vol. 3, Ecology, Culturing, Use in Aquaculture (eds P. Sorgeloos, A. Bengtson, W. Decleir & E. Jaspers), pp. 372-393. Universa Press, Wetteren, Belgium.


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