Contents

Chapter 1

General Introduction Chapter 2 Biometric Characteristics

Chapter 3

Population Parameters and Stock Dynamics

Chapter 4

Morpho- histological Developments of Male Reproductive System

Chapter 5

Morpho- histological Developments of Female Reproductive System

Chapter 6

Reproductive Characteristics

Chapter 7

Anaesthetics for Handling Management

Chapter 8

Captive Breeding and Embryonic Developments

Chapter 9

Early Larval Developments and Feeding

Chapter 10

Early developmental Deformities

Chapter 12

Literature cited

Chapter 1

GENERAL INTRODUCTION

Freshwater fish are the most imperilled vertebrate group with a projected extinction rate

of five times that of terrestrial fauna and three times that of marine mammals (Duncan &

Lockwood, 2001; Argent et al. 2003; Cooke et al. 2005). However, freshwater ecosystems may

well be the most endangered ecosystems in the world and the decline in freshwater biodiversity

is far greater than in most affected terrestrial ecosystems (Sala et al. 2000). Chapin et al. (2000)

revealed that current extinction rates of species are estimated to be 100-1,000 times greater than

pre-human rates. Globally, about 10,000-20,000 freshwater species already are extinct or

imperilled due to human activities (IUCN, 2007).

The Western Ghats part of the Western Ghats- Sri Lanka Biodiversity Hotspot in

peninsular India is an exceptional region of freshwater biodiversity (Dahanukar et al. 2011). Of

the 34 biodiversity hotspots in the world, India is endowed with a rich biodiversity of fresh

water fishes in the Western Ghats and the North Eastern Hills. The Western Ghats, the range of

hills running along India’s west coast (08019’08’’-21016’24’’N to 72056’24’’-78019’40’’E) is one of

the richest regions in terms of its biological diversity. Biodiversity studies show that the

Western Ghats is a gold mine for ornamental fishes (Mercy et al. 2009). The most recent

information’s is available by Ragahvan & Dahanukar (2013), listed 320 species of freshwater

fishes (including some secondary freshwater species, which can also live in brackish water and

marine habitats, belonging to 11 orders, 35 families and 112 genera. However, baseline

information on taxonomy and distribution of the region’s fish fauna needs to be well-

documented and is, at present, fragmented or inconsistent (Raghavan et al. 2007). Nowadays

freshwater biodiversity is facing utmost threat in India due to a number of reasons. This

includes,

Deforestation and destructive fishing

Unregulated damming of rivers

Increased accumulation of pollutants

Indiscriminate exploitation and Invasive alien species

Localised inbreeding

Different strategies have been evolves as measures to protect declining bio-diversity, such as

Habitat restoration

Species restoration, stocking and enhancement

Sustainable utilization of biodiversity services

Captive breeding and reintroduction

Sahydria denisonii was described from the Indian State, Kerala by the British ichthyologist

Francis Day in 1865, after it won an award in the 'new species' category at Singapore's Aquarama

exhibition in 2003, it exploded in popularity almost immediately. Among Kerala’s native

ornamental fish, no species has received as much global fame and hobbyist attention as S.

denisonii (Day 1865), and this endemic barb has recently become one of India’s largest exported

ornamental fish (Raghavan et al. 2008). The popularity of this species in the international trade

has resulted in unorganized exploitation in the form of a ‘boom-and-bust fishery’ with probable

negative impacts on its wild stock (Raghavan et al. 2007). Because of declining populations

(Dahanukar et al. 2004; Mercy et al. 2010; Raghavan et al. 2013) and restricted distribution

(Mercy et al. 2009; Raghavan et al. 2013) S. denisonii has been listed as endangered (Ali et al.

2011). Pushpangadan & Nair (2001) demonstrated that, knowledge on diversity, distribution

ecology, biology, and conservation and utilization prospects of diverse species is most essential

for sustainable management of endemic biodiversity. Despite being the most threatened native

fish species, S. denisonii has not been well documented in literature (Raghavan et al. 2008, 2010)

and the absence of a reliable scientific database concerning its population status, reproductive

biology and captive breeding and larval rearing technology has significantly affected

conservation efforts. This study is an attempt made to documents, some life history traits of

Sahyadria denisonii (Day 1865) for their conservation management.

Chapter 2

BIOMETRIC CHARACTERISTICS OF SAHYADRIA DENISONII

Biometric parameters are essential for different studies in biology, physiology, and ecology

of natural and exploited population of fishes. These parameters have been commonly used to

distinguish the species taxonomically, to identify stocks of fish and to separate different

morphotypes (Jayaprakash, 1974; Lourie et al. 1999; Doherty & McCarthy, 2004; Tarkeshwar et

al. 2012). Morphometric parameters, relationship between length and weight as well as the

condition factors are useful parameters for assessing the well-being of the individuals and for

determining possible differences among different stocks of the same species (King, 2007;

Hossain et al. 2013). This study aims to contribute, knowledge of biometric features of the S.

denisonii from River Valapattanam, Kerala, India.

All morphometric characters were expressed in percentage of total length (LT) and head

related measurements were expressed in head length (LH). Scattergram of morphometric

characters were plotted and the linear regression equation was fitted using least square method

described by Snedecor & Cochran (1967). The relationships were represented by the equation: Y

= a + bX. LWRs of males, females, indeterminate and pooled stock of S. denisonii were

established as follows:

Males : log W = -2.207 + 3.148 log L

Females : log W = -2.360 + 3.316 log L

Indeterminate : log W = -2.176 + 3.171 log L

Pooled : log W = -2.076 + 3.030 log L

The mean values of condition factor (K) and relative condition factor (Kn) worked out

separately for male, female and pooled samples (Fig. 2.3 & 2.4). In the present study, the

condition factor (K) varied from 0.8858 to 1.0483 in pooled sample, 0.8380 to 1.0865 in male,

0.8282 to 1.004 in female. The relative condition factor (Kn) varied from 0.8180 to 1.9187 in

pooled sample, 0.0342 to 1.9638 in male, 0.3577 to 3.0043 in female. In S. denisonii, relative

condition index (Kn) value of female is higher than that of male and Kn value variation in female

may be due to the heavier gonadal development in females (Shinkafi & Ipinjolu, 2010).

The growth of the morphometric characters in relation to the total length was noted to

be the least in the snout length (b=0.247) and the highest with the fork length (b=0.869). High

degree of correlation of morphometric characters with total length is evident from r- values

which ranged from 0.7527 to 0.9841. The morphometric characteristic such as LF, LS, DB, LPrDF,

LPrAF, LAFB, DCP, LH, HH and ED were highly correlated with total length (r >0.990), as well as HH

(0.965), ED (0.903) and LSn (0.834) were highly correlated with head length (LH). The coefficient

of correlation of head length (LH) against compared characters ranged from minimum of 0.6955

for snout length to maximum of 0.9325 for head height. The regression coefficient (r) values

shows, total length and different length relationship have highly significant correlation with

each other (p<0.05) and also have significant correlation with each other at 99.9% (p<0.01).

Based on the fin study, the fin formula of S. denisonii from River Valapattanam can be written

as: Dii-9, Pi-16, V i-8, Ai-6. Nevertheless this findings would give information to fishery biologists

about the morphometric, meristic characteristics, length-weight, length-length relationships

and growth condition of redline torpedo barb, Sahyadria denisonii (Day 1865) in the River

Valapattanam in southern India.

Chapter 3

POPULATION PARAMETERS AND STOCK DYNAMICS

The age determination in fish is one of the most important aspects in the study of their

population dynamics; it forms the basis of calculations leading to the knowledge of the growth,

mortality, recruitment and other fundamental parameters of their populations. For effective fish

resource management and conservation, stocks sizes should be assessed and the maximum

sustainable yield, fishing efforts should be determined for each fish population (Coban et al.

2013). In present study, an attempt was made in this direction on age, growth parameters,

mortality, and exploitation rate. Information from this study may be used to design fisheries

management strategies for S. denisonii population in River Valapattanam. Monthly samples

were collected from catch for aquarium trade at collection site itself from River Valapattanam

during September 2011-August 2013 (n=1037). The fish samples were collected using the

encircling net (40-60 meter in length and 1.0-2.0 meter depth) with 6 mm mesh size; nets were

also used for fish collection activities in the River by fishermen for aquarium trade. Length

frequency data were grouped into 10 mm class interval, and the data were analysed using

FiSAT-II software (Gayanilo & Pauly, 1997). An attempt was also made to determine the age

from the study of scales and Otolith.

The growth parameters observed from ELEFAN-I routines incorporated in the FiSAT-II

package were estimated as L∞= 158 mm, K = 0.8/year and t0= -0.0203 for Valapattanam River.

The longevity (tmax) of the species was calculated as 3.75 years for river Valapattanam. Based on

the values arrived at through ELEFAN-I, the Von Berttalanfy Growth Function equation

(VBGF) of S. denisonii can be express as: Lt = 158 [1- e-0.8(t+0.0203)]. Growth curve of Sahyadria

denisonii super imposed on length frequency data, restructured by ELEFAN- I. L∞= 158 mm, K =

0.8 and t0= -0.0203. On applying VBGF equation, S. denisonii attained a length during different

years of 88.15 mm at the end of first year, 126.61 mm at the end of second year, 143.9 mm at the

end of third year and 151.66 mm at the end of fourth year of life. Mortality parameters were

estimated for the pooled population of S. denisonii from river Valapattanam and, the total

mortality (Z) estimated as 2.09 year-1, natural mortality (M) as 0.83 year-1, fishing mortality

coefficient (F) as 1.26 year-1 and Exploitation rate (E) as 0.60. The relative yield per recruit

reached a maximum at an exploitation rate (Emax) of 0.737 and with an increase in the

exploitation rate, Y/R decreased.

The exploitation rate (E) is an index used to assess if a stock is overfished, on the

assumption that optimal value of ‘E’ is equal to 0.5 (Gulland, 1971; Rochet & Trenkel, 2003).

Over exploitation is now considered to be a causative factor to the decline of freshwater

biodiversity (Allan et al. 2005). Computed current exploitation rate (E=0.60) of S. denisonii from

Valapattanam River indicates that stock is currently overexploited. This is based on the

assumption that a stock is optimally exploited when fishing mortality (F) equals natural

mortality (M), or E= =0.5 (F/Z) (Gulland, 1971). The results also show that, the present level of

exploitation rate (E=0.60) is higher than the optimum exploitation rate (E0.5) which maintain

50% of the stock biomass for sustainability (E0.5=0.383), which is further indication of

overexploitation.

In present study, an attempt was also made to determine the age from the study of scales

and otolith, found that the rings found in the scales and otoliths did not show any definite

pattern and hence it was reasonably assumed that age determination based on the rings present

in the hard parts may not be dependable method in S. denisonii for the age determination. In

tropical waters, the markings found on hard parts are less distinct and their annual nature is

not accurately proved (Manoj Kumar, 2006).

Chapter 4

REPRODUCTIVE CHARACTERISTICS OF SAHYADRIA DENISONII

Among knowledge of biology, reproduction studies are important to understand the life

cycle of fishes, mainly in order to establish management policies of fishery resources and

species conservation (Casimiro et al. 2011). The different reproductive parameters like Gonado

Somatic Index (GSI), absolute fecundity, relative fecundity, oocyte diameter frequency analysis,

sexual dimorphism, sex ratio, and length at first maturity of S. denisonii have been investigated.

Length at first maturity (50% mature) in male fishes was estimated in length class of 80-90 mm

and in female a length class of 90-100 mm total length. When all month samples were pooled, a

ratio of 1.52 male: 1 female was obtained. Males outnumbered females in almost all the months

except from February to May (Table 4.1). On a monthly basis, except for February males were

dominated over females and the ratio differ significantly from the expected 1:1 ratio (p<0.05).

The mean monthly variation of gonado-somatic index (GSI) values of females during

September 2012 to August 2013. The mean gonado-somatic index (GSI) of female S. denisonii

ranged from 0.53-6.68. The mean GSI in the month of May was 0.53, which gradually increased

with a distinct upward trend in December to reach a high of 4.15 and further increased to reach

the peak value of 6.68 in January. It then declined gradually to 3.19 in March, which indicated

spawning activity.

Absolute fecundity (FA) ranged from 320-1260 (8.9-12.2 cm total length and 7.29-16.35 gm

body weight). The relative fecundity (FR) values ranged from 27.83-108.62 (64.01±23.21) per cm

total length (LT) and from 22.42- 93.06 (56.88±19.20) per gm total weight (WT) of fish. The

relative fecundity (FR) values ranged from 133.33- 350.00 (258±67.87) per cm ovary length (OL)

and 0.59-1.65 (0.96±0.24) per mg or 589.45-1645.63 (959.09±240.93) per gm ovary weight (OW) of

fish. From the ova diameter frequency distribution in immature ovary, it is observed that there

are three main classes of ova stocks includes, 32-96 µm (43.17%), 96-160 µm (37.16%), 160-224

µm (10.93%) and are up to ova diameter class 672-736 µm (0.55%). Ova diameter frequency of

all stages of growth showed have single batch of immature stocks. In early maturing ovary, it is

recorded that there are three main classes of ova stocks includes, 37.27% (96-160 µm), followed

by 25.67% (32-96 µm), 6.63% (160-224 µm) and oocyte growth up to ova diameter class 1248-

1312 µm with 0.83% of oocytes. Late maturing stage constituting are three main classes of ova

stocks includes, 96-160 µm (38.90%), 160-224 µm (14.44%), 32-96 µm (13.48%) and different

stages of oocyte developments observed up to ova diameter class 1184-1248µm (0.24%). There

was a large stock of immature ova constituting to about 47.87% of the total ova count and

ranged over a diameter of 32-224µm with maximum value at 160-224 µm (23.84%) range. The

ripe stock was about with ova size going up from 992 µm and with a mode at 1312-1376 µm

diameter class. The maximum size of ova diameter recorded during the ova diameter studies

carried out to determine the spawning frequency in S. denisonii was 1568-1632 µm. The ripening

stock contributed to the remaining 17.38% ranging from 992-1248 µm, and ripe stages

contributes 25.68% in 1248-1568 µm class. These types of ova distribution indicates spawning

may be extended over a period. Simultaneous occurrence of post-spawning and non-spawning

individuals indicates asynchronous spawning. But in present study, there is no such co-

occurrence of both ripe and spent throughout the year. Spent individuals occur during a

particular period of the year, indicating, S. denisonii is a seasonal spawner. Ova-diameter

studies reveal that species comes under the category in category- B of Karekar & Bal’s

classification (1960); category- I of Qasim & Qayyum (1961); based on oocyte size distribution of

Wallace & Selman (1981) as asynchronous ovaries, these characterized S. denisonii have a single

spawning season with protracted period.

Chapter 5

MORPHO- HISTOLOGICAL DEVELOPMENTS OF MALE REPRODUCTIVE SYSTEM

The gonad of fishes differs largely intra-specifically and inter-specifically depending on

many factors including morphology, anatomy and environmental conditions. Gonadal

development was monitored on the basis of microscopic and macroscopic appearance. The

usefulness and importance of histology techniques in reproductive studies have been widely

illustrated for fish species (Blazer, 2002). According to West (1992), histological studies provide

precise information on oocyte development but are unfortunately slow to undertake and are

expensive because they involve complex laboratory techniques. Hence, histological analysis of

gonadal development is considered the most accurate method to determine the reproductive

pattern in teleost’s (West, 1990). In this chapter, the reproductive mechanism in Sahyadria

denisonii, macroscopic as well as histological investigations were carried out.

The male reproductive system of S. denisonii is characterised by a pair of testis, are

elongated structures lying in the body cavity and ventral to the swim bladder. It leads posterio-

ventrally, two vas deferens that unite to form a spermatic duct opening to the exterior through

the urogenital aperture. The testes have a broad anterior part which tapers posteriorly and

length of the testis varies with the size of the fish. The testes of S. denisonii varied in length from

1.6 to 4.1 cm and mean weight from 0.026 to 0.834 gm. It has been found that based on shape,

size, colour, texture and histological differentiations, eight maturity stages were recognized in

S. denisonii, Stage-I (Immature virgin); Stage-II (Early developing); Stage-III (Late developing);

Stage-IV (Mature); Stage-V (Ripe); Stage-VI (Spawning); Stage-VII (spent) and Stage-VII

(Developing recovery).

The internal structure of S. denisonii testis has lobular type, in which the seminiferous

tubules are grouped in many cysts, where spermatogenesis occurs. The tubules are

anastomosing at different areas and mostly in the region of the spermatic duct. In testes of S.

denisonii, the lobules were filled with discrete nests of spermatogenetic cells in various stages of

maturation. Each nest of cells contains one spermatogenetic stage and cell size decreases

gradually by development to spermatozoa from Spermatogonia. Each spermatogonium or

germ cells in testis passes through the different stages to form mature spermatozoa. The six

stages of spermatogenesis were recognised in the testis of S. denisonii, they are primary

spermatogonia (SG1), secondary spermatogonia (SG2), primary spermatocyte (SC1), secondary

spermatocyte (SC2), spermatid (ST) and spermatozoa (SZ). The formation of these cells occurs

as asynchronous process in the lobules, where all these cells are found in one lobule. This

phenomenon and the presence of different individuals at different maturity stages in the same

period during spawning, in addition to the discharge of sperms in intermittently procedure

lead to the conclusion that male S. denisonii has a prolonged spawning season from Late

October to March. The spermatozoa of S. denisonii are characterized by a head, a short

midpiece, single flagellum, and absence of acrosome. Spermatozoa of S. denisonii are uni-

flagellated, anacrosomal, aqua-sperm type, which is typically found in a normal external

fertilizing fish.

Chapter 6

MORPHO- HISTOLOGICAL DEVELOPMENTS OF FEMALE REPRODUCTIVE SYSTEM

A complete knowledge of the reproductive system and the reproductive biology of fishes

are critical to understand the reproductive strategy and annual reproductive cycle of any given

species (Unver & Unver Saraydin, 2004). The usefulness and importance of histology

techniques in reproductive studies have been widely illustrated for fish species (Tyler &

Sumpter 1996). During oogenesis, oocytes are divided into various stages depending on the

morphology of the nucleus, cytoplasm and follicle. These stages may be grouped into the Pre-

vitellogenic, Vitellogenic, Maturation, and Atresia phases. Gonad maturation in S. denisonii has

not been studied at morphological and histological level, and their sexual maturation is still

poorly understood. In this chapter, to understand the female reproductive mechanism in

Sahyadria denisonii, macroscopic as well as histological investigations were carried out.

Stages of maturity of gonads were determined on the basis of morphological appearance

based on macroscopic as well as microscopic observations. Light Microscopic and Scanning

Electron Microscopic observation were carried out with the sample of Sahyadria denisonii. The

female reproductive system of S. denisonii is characterised by a pair of ovaries (Cystovarian

type) fused medially and lie suspended from the sides of the body cavity by mesovaria below

the air bladder. The ovaries have a broad anterior part which tapers posteriorly and its

morphology varies as well as length varies in accordance with the size of the fish and

maturational stage. The two lobes of each ovary were elongated and they were connected along

their dorsal surface by their mesentery from which they were suspended in the abdominal

cavity. The two ducts extending from the posterior ends of ovary united to form a common

oviduct leading to the urogenital pore.

The maturation cycle of ovary of S. denisonii was followed during present investigation by

defining the following eight stages of maturation, Stage-I (Immature virgin), Stage-II (Early

developing), Stage-III (Late developing), Stage-IV (Mature), Stage-V (Ripe), Stage-VI (Partially

spent), Stage-VII (spent) and Stage-VIII (developing recovery). Oocyte stages were usually

identified, based on the size, amount and distribution of various cell inclusions like nucleus,

nucleolus, and other cytoplasmic inclusions like yolk nucleus, yolk vesicles, yolk granules and

lipid globules. Each ovary is covered by a thin peritoneum beneath which lies the thick tunica

albuginea containing blood vessels, connective tissues and smooth muscles. The innermost

layer is a layer of germinal epithelium which projects into the lumen of the ovary (ovocoel)

forming ovigerous lamellae, and the oogonia were appears on these lamellae.

Each oogonium in S. denisonii passes through the following stages to form mature ova, and

different stages of maturation are, Oogonia stage, Chromatin nucleolus stage, Early

perinucleolus stage, Late perinucleolus stage, Early yolk vesicle stage, Late yolk vesicle stage,

Early yolk globule stage, Late yolk globule stage, Migratory nucleus stage, and Ripe egg stage.

Group synchronic developments of oocytes with elven histological stages in the cystovarian

ovary which passed through eight morphological maturity stages and a fairly prolonged single

spawning period were noted characteristics of the ovarian cycle in S. denisonii.

Chapter 7

ANAESTHETICS FOR HANDLING MANAGEMENT

The use of anaesthetics in fisheries and aquaculture research greatly facilitates in

procedures including induction of breeding, handling during stripping and transport of brood

stocks. Anaesthesia and sedation is usually essential to minimize stress and physical damage in

handling the fish for routine operations (Iwama et al. 1997; Ross et al. 1999). The anaesthetics

used in this study to determine the efficacy in S. denisonii are Clove oil, MS-222 and 2-

phenoxyethanol. The clove oil administered at the concentrations ranging from 20 to 50 mg/L

resulted in progressive anaesthesia. According to these results, the induction time was less than

three minutes for dose of 30 mg/L, so the most effective concentration of clove oil in the

induction of anaesthesia for S. denisonii appeared to be 30 mg/L. Time taken to reach different

stages of anaesthesia was also recorded. At 30 mg/L, Eugenol induced anaesthesia within 31

seconds and the time to reach a complete anaesthesia state (135 sec) was significantly different

(P<0.05) from the other dosages (20, 40 and 50 mg/L).

The induction time of S. denisonii decreased with increasing concentrations of MS-222.

The induction time was less than three minutes for a dose of 150mg L and therefore this was

considered as the best effective concentration of MS-222 for the induction of anaesthesia in S.

denisonii. At 150mg L, the time to reach a complete anaesthesia (stage IV) (165±10 seconds) was

significantly different (P<0.05) from the other dosages (50, 100 and 200 mg L -1) (Table 8.4). At

lower concentrations (50mg L-1 and 100mg L-1), more time (746±56 seconds and 506±20 seconds)

was required to reach stage I and stage IV, respectively. There was a clear linear pattern of

decreasing induction time with increasing concentration of the anaesthetic, with the longest

induction times for fish in the group exposed to 100mg L-1 of MS-222 (506±20 seconds) and the

shortest for fish exposed to 200mg L-1(97±5 seconds). Induction times generally decreased

significantly with increasing doses for MS-222. In S. denisonii, the lowest induction time (<180

seconds) was observed at 500 μl/L-1 of 2-phenoxyethanol and therefore this dose was

considered as the best effective concentration for anaesthesia in S. denisonii. At 500 μl/L-1 of 2-

phenoxyethanol, the time to reach stage- IV of anaesthesia (173 ± 7 seconds) and recovery time

(129±41 seconds)was significantly different (P<0.05) from the other dosages (200 μl/L-1, 300

μl/L-1, 400 μl/L-1and 600 μl/L-1).

Chapter 8

CAPTIVE BREEDING AND EMBRYONIC DEVELOPMENTS

The major conservation objective, perhaps fortified by legislation, must be habitat

restoration and management, but short-term programmes can usefully involve translocations,

captive breeding and cryopreservation. Conservation status of freshwater fishes in India is

likely to reach a conclusion that the existing protection given to most of the indigenous species

is inadequate in terms of legislative, establishment of induced breeding strategy and population

status. Captive raised specimens can be re-introduced to the natural habitat thereby protecting

the species from extinction. Captive breeding in the long term is not appropriate for many fish

species but could be an important 'last resort' measure for endemic, endangered species which

may otherwise become extinct in the wild.

This chapter documents the captive breeding and early embryonic development of

Sahyadria denisonii under controlled conditions. Breeding experiments were carried out over a

period starting from December 2009 to January 2012, including its F1 generation (n=10). The

results of this study gave a better understanding for the breeding protocol of S. denisonii. In the

present study, maturation of egg of S. denisonii was determined by following, 1) morphological

appearance of eggs and 2) Method of movement of the nucleus. Brood female fishes were

anaesthetized, with MS-222, Clove oil or 2-phenoxyethanol. The administration of ovaprim is

based on the Linpe method. Intra muscular injection at the base of the anterior part of dorsal

fin was given to anaesthetized S. denisonii both male and female at a rate of 0.4ml ovaprim/kg

body weight. In present study, we succeeded in obtaining larvae of S. denisonii by artificial

fertilization by using ovaprim as inducing agent. The embryonic period starts when the eggs

fertilized by a sperm and ends when the embryo has attained the generalized organ systems as

they appear in common in all the fish. The egg shell was broken due to rapid shaking

movements of the body at 36th hour and the head emerged out first, followed by the tail. In the

present breeding trial, latency period observed as 12.78±0.83 (hrs±s.d), fertilization rate as

86.11±5.23 (%±s.d) and hatching rate as 85.89±2.98 (%±s.d). F1 generation was also successfully

bred in the hatchery through hormone application and hatch out young ones (F2-generation)

were reared in captive condition, So the technology is standardized for their commercial

production.

Chapter 9

LARVAL DEVELOPMENTS AND FEEDING OF SAHYADRIA DENISONII

For the conservation of fish, one alternative could be the development of breeding and

larval rearing technology, which requires knowledge on their nutritional requirement from

hatchlings to adult stage (Singh et al. 2012). Success of larval rearing depends mainly on the

availability of suitable diets that are readily consumed and that provide the required nutrients

to support higher growth and health. Fish larvae are the smallest self-supporting chordates and

in order to escape predation and to increase their chances of survival, they need to complete

their morpho-functional systems. Studies on the nutritional physiology of larval stages provide

the basis for defining the length of the larval period and for understanding the quantitative and

the qualitative feed requirements of the larvae. This chapter describes two objectives (1) the

morphological description of the larval period and (2) to study the growth performance with

different diets for S. denisonii under controlled conditions. Larval development were

documented and photographed with binocular stereo microscope (LABOMED) fixed with

digital camera (Canon Power Shot-A570). After observation the specimens were fixed in 5%

buffered formalin. Descriptions of pigmentation of newly hatched, yolk sac and on growing

larvae were made with reference to different body regions. The stage of larval ontogenesis was

assessed on the basis of standard length and the main external morphological features, which

are related to age, given as Days post hatching (DPH). Pre flexion, Flexion and post flexion

stages of larvae in relation to notochord development were assessed by morphological

assessments.

The larval life of S. denisonii passes through three transformable stages via, Pre flexion,

Flexion and Post flexion. Four different types of diets such as, micro worms (MWD), Artemia

flakes (AFD) of OSI Feeds, USA, Higashi feed (HFD) of Higahsi Aqua feeds pvt. Ltd, Kerala

and Varna feed (VFD) of Central Marine Fisheries Research Institute (CMFRI), Cochin, Kerala

were used in the experiment. %). In the present study, highest weight gain was recorded in

AFD (50.0% protein) and lowest weight gain in larvae fed with HFD (39.0% protein). The

results of the present study clearly showed the effect of dietary protein on the growth of S.

denisonii. Significantly higher weight gain (6.21±0.05 mg) was observed in larvae fed with AFD

(p<0.05) followed by VFD (4.90± 0.71 mg), MWD (2.45±0.07 mg) and lowest with HFD

(2.13±0.04 mg) (Table. 3). Significantly higher increase in length (p<0.05) was observed in VFD

(35.5±0.14 mm) followed by AFD (33.3±0.07 mm), MWD (26.0±0.14 mm) and lowest with HFD

(21.5±0.07 mm).

Chapter 10

EARLY DEVELOPMENTAL DEFORMITIES IN SAHYADRIA DENISONII

Most of skeletal deformities appear during the larval and juvenile stages, where many

biological processes take place for organogenesis, morphogenesis and metamorphosis in a very

short time (Fernandez et al. 2008). Skeletal deformity is one of the most crucial problems in fish

culture, since it reduces the growth and survival of affected fishes. In addition, skeletal

deformities affect body form, which is associated with viability, depression of price, and lower

market demand for the deformed fish (Daoulas et al. 1991). In hatchery production, deformities

are main problems, as they reduce the market value of the produced fish by affecting their

external morphology, growth and survival and they lower the swimming and feed

consumption performances of hatchery-reared fish.

Abnormal specimens were anaesthetized with MS-222, and morphological and anatomical

terminology relating to the abnormality followed that used by Al-Harbi (2001). Morphological

abnormality was photographed with a digital camera (Nikon Coolpix L22) and deformity was

further examined by digital X-ray system (Fujifilm FCR Capsula XL II Reader). For the

comparison of deformity, a normal fish specimen was also radiographed. With the help of an X-

ray radiograph, skeletal deformities were better visualised, because radiography is faster and

simpler to perform than standard histological methods for examining skeletal anatomy and

skeletal development (Olatunji-Akioye, 2010). Two deformed specimen of S. denisonii (Total

Length=57mm, Standard Length=44mm, Total Weight=19.5mg) was caught by drag net from

Vallithode (12.0304 latitude and 75.7154 longitudes) region of River Valapattanam in August

2013. Another deformed specimen of S. denisonii (Total length=42mm, Standard length=29mm,

Total weight=79 mg, Age 0+) was caught by drag net from River Valapattanam (11.9499

latitude and 75.7338 longitudes) in May 2013.

Different types of morphological as well as osteological anomalies were recorded in this

hatchery produced young ones of S. denisonii. The deformities were externally apparent

compared to normal specimen and observed deformities includes, semi-operculum, vertebral

deformity, head deformity, mouth deformity, fin deformity and also multiple deformities. The following

types of malformations were observed in the abnormal S. denisonii. Even though the exact cause

of deformity was not determined; unfavourable abiotic conditions, inappropriate nutrition,

early developmental errors and genetic factors or a combination of these factors could all have

been involved in the pathogenesis. But in the absence of exact evidence, no single specific

reason for deformities in S. denisonii can be established.

LITERATURE CITED

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