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November | December 2011

Feature title: Aquarium Fish Feeding

The International magazine for the aquaculture feed industry

F: Aquarium fish

Aquarium fish hobbyists can enjoy an impressive range of species, whose number is increasing every year.

In response to the growing aquarists’ needs manufacturers introduce foods with more and more sophisticated formulas. However, data concerning dietary habits of wild specimens are rudimentary and extremely hard to obtain. The knowledge about fish’s needs comes from observation rather than rigorous research.

Therefore, the common practice is to use research carried out on fish for human consumption instead despite the fact that it is not possible to create and maintain natural network of feeding relations in aquarium and many species-typical behavior patterns are simply not observed.

No wonder that a diet of aquarium fish is becoming more universal.

In the wild fish feed on insects, molluscs, crustaceans, fish, plants, algae, etc. These foods differ in terms of quality and quantity of nutrients.

In addition, fish’s diets vary throughout the year, as food availability varies depending on the season. In the absence of their primary food, fish are forced to resort to less palatable alternatives, which they have declined so far.

It’s not possible to imitate natural living conditions of wild fish but you can compose a diet based on products with nutrient-rich compositions to diversify their diet, hence prevent nutritional deficiencies and numerous medical disorders. The most vulnerable is the hatch. Any deficiencies it experiences during this period can lead to deformities and devel-opmental disorders.

For instance, Artemia nauplii, commonly used for rearing fry, lead to the decalcification of bones and reduction of the survival rate, if not supplemented by other foods.

Nutritional requirementsIn terms of their nutritional requirements

ornamental fish can be divided into herbivores, omnivores and carnivores.

Prepared foods for herbivorous fish should be characterised with high content of plant material, including spirulina, chlorella, Kelp algae, spinach, nettle, etc. They should also be fed with fresh or frozen plants, mostly spinach, broccoli, zucchini, carrots, etc.

For carnivorous fish, which in the wild feed on fish, roe, fry and invertebrates, there’s a choice of frozen foods (krill, shrimps, fish fillets, squid, Daphnia pulex, Artemia, bloodworms, Tubifex etc.) and live foods (fish, Daphnia, Artemia, bloodworms, Tubifex, glassworm etc.) and multi-ingredient and high-protein prepared foods.

Prepared foods for aquarium fish

Prepared foods available on the pet market can be divided into: multi-ingredient univer-sal foods, used in feeding of most popular aquarium fish species and specialist foods, dedicated to particular species or groups of fish with sophisticated dietary demands, such as Tropheus cichlids, Malawi cichlids of mbuna group which feed on periphyton, breeding discus, goldfish, red parrots and algae-eaters from Loricariidae family etc.

A special group of foods are products enriched with various natural resources that improve fish’s health, enhance their colora-tion and increase their resistance to diseases.

The diversity of formulas is accompanied by a variety of forms in which prepared foods are available, so you can choose product perfectly adjusted to the size of your fish’s mouth and their way of feeding (from the surface of the water, its middle layers or from the bottom - see Figure 1).

The best feeding solution for bottom-feeders are granules and

tablets. Fish feeding in the middle layers of the tank or at the bottom prefer slowly sinking granules, which turn out particularly effective in multi-species tanks with fish eating in various parts of the aquarium.

Fish with small mouth eating under the surface of water will choose flakes, which prove highly effective in tanks where intraspecific competition takes place and weaker fish have a limited access to food. Flakes, floating all over the tank, are easily accessible even for smaller and weaker fish.

Tablets are recommended for timid fish, as they can be placed in fish’s favourite hiding places and for feeding the fry, due to the small particles that make up the tablet.

Immunity enhancing components

Prevention in fish is more effective than medical treatment. Well-nourished fish with a strong natural resistance to diseases is more likely to cope with stress (transport from farms to wholesalers, store, the customer’s home) and pathogens. In prepared foods for orna-mental fish one can find numerous substances and resources, whose components enhance the immune system, for example stabilised

AQUARIUM FISH FEEDING

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vitamin C, beta-glucan, unsaturated fatty acids, spirulina, Kelp algae, chlorella, etc.

Stabilised vitamin C is a L-ascorbyl-2-polyphosphate resistant to high temperatures. Vitamin C reduces stress, stimulates the immune system, strengthens blood vessel’s walls and accelerates wound healing.

Unsaturated fatty acids (UFAs), including long-chain fatty acids Omega-3 and Omega-6, accelerate the regeneration of tissues, including skin, improving its function as a protective barrier.

Moreover, they are a building material of hormone-like cellular messengers - pros-taglandins and reproductive cells. Part of the demand for Omega-3 and Omega-6 fish cover themselves by producing them from simple UFAs, which they obtain from food.

However, carnivorous and marine fish should be supplied with Omega-3 fatty acids, because their ability to process them from simple UFAs is small.

Beta-1.3/1.6-glucan - a polysaccharide derived from yeast’s cell walls - is a natural immune stimulator that directly affects mac-rophages, increasing their capacity for phago-cytosis of alien cells and their own cancer cells.

Extremely valuable components of foods for aquarium fish are algae and spirulina (Arthrospira platensis).

The share of the latter in fish feed depends on, inter alia, a very high protein content (55-70 percent) characterised by a high digestibility (90 percent).

In addition, protein of Spirulina contains most essential amino acids for fish (if not all).

The cell’s walls of this cyanobacterium are composed of mucopolysaccharides, which act as immunostimulators. In the cells of spirulina one should find three times more chlorophyll than in plants. Chlorophyll reduces the number of putrefactive bacteria in the gastrointestinal tract. The high content of carotenoids, especially beta-carotene, makes foods with spirulina intensify coloration in fish, which is essential in case of colourful breeding

forms. Thanks to so many different substances spirulina enhances vitality and encourages the immune system.

Other relatively common algae supple-ments of aquafeed are chlorella and Kelp algae.

Chlorella is known for its high concentra-tion of chlorophyll (seven percent in the dry matter) and large protein content (50 percent in the dry matter), rich in essential amino acids.

Health benefits are attributed to Chlorella Growth Factor, rich in nucleic acids. Kelp algae is a mixture of marine seaweed belonging to the brown algae, which are rich in minerals, including well-assimilable organic iodine compounds, UFAs, and vitamins. Their addition has a beneficial effect on metabolism and general condition of the fish.

Herbs in the aquariumNot only have the herbs been applied to

treat people, they are also commonly used as a dietary supplement in feeds for livestock and domestic pets. Herbs enhance food palatability, stimulate animals’ appetite, aid digestion and improve overall health.

They also act as an anti-inflammatory, antidiarrheal and bacteriostatic agents.

Herbs are also present in the aquarium. They play an important role in the preparation of water and are used as a com-ponent of both prepared foods and those pro-duced in house conditions.

In Europe there are 25 species of basic herbal raw materials, includ-ing garlic and common nettle, which are used in foods for ornamental fish.

To manu-facture pre-pared food pro-ducers also use plants rich in the so called fitamins, which act on the

body in a manner similar to vitamins. But unlike the vitamins, they do not have to be delivered each day. Fitamins are present in vegetable and herbal plants. They regulate metabolic processes, detoxicate body and enhance over-all condition. Fitamins include among others: polyphenols (flavonoids and phenolic acids),

sulfur compounds (such as allin in garlic), tan-nins and carotenoids. The exceptional sources of fitamins in foods for fish are garlic, spinach, spirulina and Kelp algae.

Garlic (Allium sativum) is a well-known spice and herbal plant. Its cloves are composed of sulphur-containing compounds, inter alia, allin which becomes allicin when garlic is crushed. This is allicin to which garlic owes

by Aleksandra Kwaśniak-Placheta1 and Leszek Moscicki2

1Tropical - Tadeusz Ogrodnik, 25 Opolska Street, 41-507 Chorzow, Poland

2Lublin University of Life Sciences, 44 Doświadczalna Street, 20-280 Lublin, Poland

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F: Aquarium fish

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However, using Tubifex from polluted environment can lead to poisoning of fish. Tubifex and chirono-mids are both added to prepared foods and subjected to freeze-drying process.

Daphnia is a source of protein and fat (including UFAs).

However, it contains a small number of highly unsaturated fatty acids: EPA and DHA. Protein content (20-25 percent) and fat content (2.4-20 percent) vary widely depending on the feed base of the tank, where crustaceans live and on the season.

The composi-tion of Daphnia resembles freshwater shrimp: Gammarus pulex, which contains similar amount of valu-able protein. It is a good source of unsaturated fatty acids, including n-3 acids, and carotenoids.

One kilogram of dry matter of Gammarus pulex contains about 700-800mg of carote-noids (with astaxanthin share of 40 percent).

Artemia salina (Artemia sp.) is a popular food for ornamental fish. It is used in its larval form (also independently hatched in house conditions), frozen or freeze-dried adult forms, or as an additive to prepared foods. Newly hatched larvae of Artemia contain 89 percent water, 6.7 percent crude protein, 2.1 percent fat, 1.1 percent ash and after drying � 58 per-cent protein, 20 percent fat and 10 percent ash.

Adult Artemia contains 60 percent protein, 13 percent fat and 12 percent ash in the dry matter.

When composing a diet for your fish, follow the basic nutritional principles, taking into account the nutritional value of main nutrients. Compacted information concerning this issue is shown in Figures 2 and 3.

When composing a diet for your fish, take into account the proportions of multi-ingredient, vegetable and high-protein foods in the diagrams shown on Figure 3.

Conclusive remarksManufacture of aquaristic feeds which meet

high quality standards require an extensive know-how, the accuracy of processing and the

and smell of the food. This is of particular importance in case of feeding wild caught specimens and commercial farming fish, which aren’t used to eat prepared foods and need encouragement. Apart from valuable pro-tein Krill provides fish with unsaturated fatty acids, out of which 40 percent are PUFAs (polyunsaturated fatty acids), including 14.7 percent EPA and 8.3 percent DHA. Krill is also a great source of carotenoids � natural pigments that enhance fish’s coloration.

Chironomids – red mosquito larvae – constitute a high-protein food, which con-tains around 60 percent crude protein and 10 percent fat in the dry matter. Due to the low content of unsaturated fatty acids (approximately 14 percent) and high content of saturated fatty acids (approximately 28 percent of palmitic acid) the food cannot be used too often, because it can cause fatty degenerations and deficiency of PUFAs. Due to its high pro-tein content it is a perfect food for spawners and fish weakened by illness or long transport,

especially that fish take it very eagerly.Tubifex (Tubifex tubifex) lives in bottom

sediments, where they feed on organic matter, algae and bacteria that live in them. These organisms are very resistant to vari-ous pollutants that can accumulate in them.

its strong antiseptic prop-erties and its characteristic flavour. Garlic also contains flavonoids, pectins, mucilages, several vitamins and trace elements.

Before it started to be widely used in prepared foods for fish, it had been added by fish enthusiasts to mixtures they had prepared in their homes, especially the ones for the discus, often targeted by gastrointestinal parasites.

Foods for ornamental fish also utilise nettle (Urtica dioica). The active substanc-es in this plant are organic acids, flavonoids, carotenoids, tannins and others. Thanks to them, nettle regulates digestion. As a food sup-plement it has a beneficial influence on digestion and provides a number of fitamins, vitamins and trace elements.

Invertebrates used in feeding of ornamental fish

Before fish enthusiasts could take advantage of convenient and easy-to-store prepared foods, they had had to use natural foods, which they fished or bred themselves.

Despite many advantages the use of living organisms in the aquarium has one fundamen-tal flaw – the organisms derived from nature can be a source of dangerous pathogens. To avoid this threat you can chose frozen, dried and freeze-dried products. Invertebrates have also become the essential ingredient of pre-pared foods (see Table 1).

Antarctic Krill (Euphausia superba) is a source of easily-digestible protein, rich in essential amino acids. It is readily consumed by fish, especially in its processed form as an additive in flakes, granules and tablets. It is also characterized by a high palatability, resulting from the presence of amino acids (glycine, pro-line), nucleic acids and TMAO (trimethylamine

oxide). These substances affect the

taste tein content it is a perfect food for spawners and fish weakened by illness or long transport,

affect the taste

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Opuszyński K., (1979), Podstawy biologii ryb (in Polish), PWR i L, Warszawa;

Sushchik N.N. et al., (2003), Comparison of fatty acid composition in major lipid classes of the dominant benthic invertebrates of the Yenisei river, Comparative Biochemistry and Physiology Part B 134, 111–122;

Tacon A.G.J., (1987), The nutrition and feeding of farmed fish and shrimp - a training manual 2. Nutrient sources and composition, A report prepared for the FAO Trust Fund GCP/RLA/075/ITA Project Support to the Regional Aquaculture Activities for Latin America and the Caribbean, Food And Agriculture Organization Of The United Nations, Brazil;

Ciferri O., (1983), Spirulina, the edible microorganism, Microbiological Reviews, December, 551-578;

Clifford Chan, (2003), Exotic Discus of the World, Clean Ace Printing Press, Singapur;

Floreto E.A.T; Brown P.B.; Bayer R.C., (2001), The efects of krill hydrolysate-supplemented soya-bean based diets on the growth, colouration, amino and fatty acid profiles.; Aquaculture Nutrition 7; 33-43;

Gaillard M. et al., (2004), Carotenoids of two freshwater amphipod species (Gammarus pulex and G. roeseli) and their common acanthocephalan parasite Polymorphus minutus, Comparative Biochemistry and Physiology, Part B 139,129–136;

Ghioni C., Bell J.G., Sargent J.R., (1996), Polyunsaturated Fatty Acids in Neutral Lipids and Phospholipids of Some Freshwater Insects, Comp. Biochem. Physiol. Vol. l14B, No. 2, pp. 161-170;

Hasik J., (2001), Usprawnienia dietetyczne procesów metabolicznych. Co to sń fitaminy?, (in Polish), Postńpy Fitoterapii nr 6, (2-3);

Kibria G. et al., (1999), Utilization of wastewater-grown zooplankton: Nutritional quality of zooplankton and performance of silver perch Bidyanus fed on wastewater-grown zooplankton, Aquaculture Nutrition 5, 221-227;

Lutomski J., (2001), Znaczenie ziół w terapii i dietetyce (in Polish), Postńpy Fitoterapii 6, 2-3;

use of a modern and sophisticated technologi-cal equipment.

It is much more complicated than the production of aquafeed for fish farming.

The quality of aquarium foods is immediate-ly visible after the application, in the literal sense. Aquarist will immediately notice the loss of every single fish or the contamination of water in the tank caused by the dust from crumbled food, quickly decaying wastes or colorants.

Despite the wide range of various foods on the market, only few of the offered products meet the highest nutritional criteria, can guar-antee safety of feeding and do not contaminate the aquatic environment.

The form and functionality of the packaging units are equally important. The expectations of the customers in this aspect are justifi-ably high as the options are impressive: con-tainers acting as feeders, helping keep food in sterile conditions, transparent, but at the same time protected from ultraviolet radiation (see Figure 4). These challenges can be met only by few companies.

LiteratureBernard J.B., (1997), Feeding captive insectivorous animals: nutritional aspects of insects as food, Nutrition Advisory Group Handbook, Fact Sheet 003;

Table 1: The content of crude protein, crude fat and ash in selected aquatic invertebrates (% of the dry matter)

Raw material Crude protein

Crude fat Ash

Artemia - adult form 60,0 13,0 12,0

Artemia larvae - nauplii 58,0 20,0 10,0

krill 70,0 10,4 12.6

Chironomidae 60,0 10,0 11,0

Daphnia 50,0 2,4 19,0

Tubifex 47,8 20,1 4,5

28 | InternatIonal AquAFeed | november-December 2011 november-December 2011 | InternatIonal AquAFeed | 29

F: Aquarium fish

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18 | InternatIonal AquAFeed | november-December 2011

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