Breeding performance of Macrobrachium rosenbergii in captivity

The key factor in success of a Macrobrachium hatchery is to yield maximum number of larvae with minimum number of brooders. Suitable environmental conditions were provided and the breeding performance of females of M. rosenbergii was observed. A total number of 140 females brought from wild were used for this purpose. Each female was tagged and given a code number which made it possible to record the gestation period, interbreed period, number of breeding and larval yield of individual female during each breeding. Females were found to breed six times during the ten months duration. Of the total females studied, 99.12 % bred once, while only 2.16 % females bred six times in a total span of ten months. The average number of larvae decreased successively from first to fourth breeding. The average interbrood period was minimum between the first and second breeding and maximum between the fourth and fifth breeding. The highest average larval yield of 25,428 was recorded in the first breeding, the lowest of 4,596 in the fourth breeding. The possible reasons for variations in interbrood period and larval yield are discussed.

Studies on the performance of Ovatide on breeding of Indian major carps

The paper deals with the experimental studies on breeding of Indian Major Carps - Catla catla (Valenciennes), Labeo rohita (Hamilton), Cirrhinus mrigala (Hamilton), & Labeo calbasu (Hamilton) with the help of 'Ovatide' which is being used as an alternative inducing agent for commercial seed production. This study has been conducted for six consecutive months (April - September, 2000) in a stone-pitched breeding channels of a farm located at Midnapore District, West Bengal. The doses of 'Ovatide' (0.5 ml/kg of fish weight) remained same for each female species during the entire study period and males were released without any dose. The physicochemical parameters of water during different months were estimated. The latency period and fertilization percentage varied in different months and species. The results confirmed that 'Ovatide' can be used successfully in a much more cost-effective way for induced breeding of carps, even in rural fish farms with morrum-pitched breeding channels.

Effects of different dietary levels of vitamin E on the breeding performance of Heteropneustes fossilis (Bloch)

Experiments on the study of different dietary levels of vitamin E on the growth and breeding performance of Heteropneustes fossilis brood fish were carried out in two phases. The first phase consisted of studying its ovarian development and the second phase on breeding performance. Sixty female fishes were stocked in twelve experimental chambers of a raceway. The effects of four dietary vitamin E levels viz. 0 (served as control), 50, 100 and 200 mg/kg feed, on the somatic growth, ovarian development of brood fish and on their breeding performance were studied. Each treatment had three replications. It was observed that body growth in terms of length and weight was best with 0 mg vitamin E/kg feed and 200 mg vitamin E/kg of feed gave poorest result. The gonado-somatic index and fecundity, however, was highest in the fish fed with 100 mg vitamin E/kg of feed. In case of breeding performance such as ovulation rate, fertilization rate, hatching rate and survival rate, the best result was obtained with 200 mg vitamin E/kg of feed. The overall result of this experiment indicates that 200 mg vitamin E/kg of feed is the best vitamin E dose for H fossilis brood and vitamin E content has a positive impact on ovarian development.

Development of artificial breeding techniques for long-whiskered catfish, Sperata aor and giant river catfish, Sperata seenghala of Bangladesh

Sperata aor and S. seenghala are the two important native catfishes of Bangladesh but commercial farming of these species is not possible due to lack of naturally collected or artificially produced seeds for stocking. Attempts were made to develop techniques for seed production by artificial breeding and nursery-rearing of fries of these catfishes. A total of 60 S. seenghala (750-1,500 g) and 10 S. aor (600-1,000 g) broods were collected from the Brahmaputra river-basin and floodplains in Mymensingh region four months prior to their breeding season. The collected brood fishes were reared in separate earthen ponds with supplementary feeds comprising of rice bran (40%), mustard oil cake (29%), fish meal (30%) and vitamin-premix (1 %). Three experiments were conducted to optimize the hormone dose. A total of nine S. seenghala females weighing from 750 to 1,500 g were given an initial and resolving dose of 12-20 and 16-24 mg PG/kg body weight, respectively. The males weighing from 650-950 g were administered a single dose of 18-26 mg PG/kg body weight at the time of the time of administering the resolving dose to the females. The females ovulated partially and the eggs were examined under a compound microscope, but most of them were found to be less ripe or damaged. Collection of milt by stripping the males was not successful. The testes were taken out and sperm were observed to be non-motile and less developed. In view of stimulating natural propagation of S. seenghala, artificial holes (nests) were constructed in the pond bottom. Each hole was 0.7 m in diameter and 0.3 m in depth. A total of 10 holes were made and then 10 pairs of S. seenghala breeders (800-1,200 g) were stocked in the pond. In mid February, 3,000 fry of S. seenghala with a mean length of 4.60 cm and weight of 0.36 g were collected by repeated netting followed by drying of the pond. The fry were then stocked in a nursery pond and fed with commercial feed (SABINCO starter-1). The average length and weight of the fingerlings were 9.01 cm and 3.95 g, respectively and the estimated survival was 60% after two months of rearing. S. aor did not respond to natural spawning. Further study is essential to develop techniques for their successful artificial and natural breeding.

Breeding biology and monosex male seed production of Genetically Improved Farmed Tilapia (GIFT) strain of Oreochromis niloticus L. in Bangladesh

A study on the breeding biology of the GIFT strain of Nile tilapia, Oreochromis niloticus, was conducted for a period of five months. The sex ratio of the parent individuals was optimized for performance in spawn production, where the best results were obtained with a sex ratio of female to male of 4:1 compared to those of 3:1 and 2:1. The diameter of eggs obtained from the GIFT stock had major and minor axes of 2.19±0.09 and 1.72±0.07 mm, respectively, with no significant differences between the treatments. The average number of eggs produced was 392±22 per female, with fertilization and hatching rates ranging between 94-96% and 85-88%, respectively. No significant variation was observed between the treatments. Breeding frequencies per female in the three treatment groups ranged between 10-40 days and the highest value was obtained at a female to male sex ratio of 4: l. In an other experiment, l7 aMethyltestosterone (MT) was applied orally to the fry at their first feeding stage with treatments- 1, 2, 3 and 4 at the dosage of 100, 80, 60 and 40 mg/kg feed respectively, for the period of 28 days. The mean percentage of males obtained in treatments, 1, 2, 3 and 4 were 98, 97, 95 and 68, respectively. Treatments-1, 2 and 3 did not differ significantly (P>0.05) from each other but treatment 4 showed significant variation (P<0.05) from other treatments. The results showed that MT-100, 80 and 60 mg/kg feed administered for 28 days produced close to cent percent male population of the GIFT strains in aquaria.

Effect of carp PG doses on induced breeding of Shing, Heteropneustes fossilis (Bloch)

Five hormone doses viz. 25, 50, 75, 100, and 125 mg of carp PG/kg of body weight of the recipient fish were tested and they were designated as T1 T2, T3, T4, and T5 respectively. Significantly higher fertilization (98%) and hatching rates (38%) were obtained from T3 (75 mg of carp PG extract/kg body weight). While T4 (100 mg of carp PG extract/kg body weight) and T5 (125 mg of carp PG extract/kg body weight) gave the highest (90%) ovulation rate. In June and July the highest fertilization rate of 96 and 96.4% respectively and hatching rate 42.5 and 48.7% respectively were obtained. In over all consideration carp PG extract at a dose of 75 mg/kg body weight appears to be the suitable dose for induced breeding of H. fossilis and June and July are the suitable time for its induced breeding.

Experiments on the induced breeding of milkfish, Chanos chanos (Forsskal) in 1978

Results indicated that a female having eggs with an average diameter of < 0.7 mm did not respond well to the hormone injections.

Induced breeding of Indian carps using Des Gly^10 [D-Ala^6] LHRH ethylamide

Details are given of a study conducted in order to determine the efficacy of Des Gly^10 [D-Ala^6] LHRH ethylamide in the induction of spawning in Cirrhinus mrigala and Labeo fimbriatus . Findings shows this LHRH analogue to be a promising substitute for the pituitary gland extract which is currently used. Further studies are required to standardize the dose and method of administration in the various cultivable species in India.

Captive breeding and embryonic development of honey gourami, Colisa sota (Ham.-Buch.)

Honey Gourami, Colisa sota, has high ornamental as well as food value. The natural resources of this species are gradually declining, due to destruction of its habitat, over fishing for aquarium trade and human consumption. The fish was bred in captivity under controlled environment. It laid about 200-400 eggs in bubble nest built by the male. Hatching started within 28-30hrs. after egg laying. The hatchlings became free swimming by 3rd to 4th day of hatching. The male showed territoriality and parental care by guarding the eggs and hatchlings. The larval survival was 30-35%. The breeding behavior, embryonic and post embryonic development of the fish were studied.

Spawning behaviour and induced breeding of an estuarine catfish, Mystus gulio (Ham.)

Spawning behaviour of hormone induced estuarine catfish, Mystus gulio was observed in captive condition. Spawning activities that include pairing, chasing and resting, nudging, and twisting, started about 5 hours post injection and ended with release of eggs within 1-2 hours of courtship. Three different dosages of "ovaprim" (1 ml/kg, 1.5 ml/kg, and 2 ml/kg in a single dose) were used in induced breeding of M gulio. The latency period was less (6-7 hours) with the dose of 1.5 and 2 ml/kg, while it was more (7-8 hours) with that of 1 ml/kg. However, all females spawned successfully with each of three different dosages, without any significant differences in the rate of fertilization and hatching. Eggs under all hormone dosages hatched between 18-20 hours after spawning. The hatching rate with 1, 1.5, and 2 ml/kg varied from 71.3-72.7%, corresponding to the fertilization rate of 80.7-84.7%.

A comparative study on the induced breeding and in vitro fertilization performance by various inducing agents in catfish, Heteropneustes fossilis (Bloch)

Brood catfish, Heteropneustes fossilis were collected from Tamirabarani river basin of Tamil Nadu, India and kept in cement tanks. Three inducing hormones viz, Ovaprim, Ovatide and WOVA-FH were injected at the rate of 0.5, 1.0, 1.5 and 2.0 ml/kg body weight in order to induce oocyte maturation and ovulation. After 10-13h of injection at a water temperature of 27±-0.5°C, stripping of eggs and in vitro fertilization was done. Ovaprim gave maximum (94.67%) hatching rate followed by Ovatide (90.33%) and WOVA-FH (77.33%).

Preliminary success on hormone induced captive breeding of goldspot mullet, Liza parsia (Ham.)

An attempt was made to breed goldspot mullet, Liza parsia in captivity through hormone induction. The fish started spawning 35-36 hours after a single dose of 2ml ova prim per kg body weight. Hatching of fertilized eggs completed within 42-48 hours after spawning. The mean hatching rate (%) was 71.33±12 corresponding to the fertilization rate (%) of 64±12. The larvae started its first external feeding on the third day and attained a length 2.5±0.25 mm. The salinity of both breeding and rearing cisterns was 20‰ and temperature was maintained at 22-23°C.

Effects of dietary vitamin E on the growth and breeding performance of Ompok pabda

A 90 day feeding trail was conducted to investigate the effect of vitamin E on the growth and breeding performance of Ompok pabda. A total of 84 healthy female brood fish (41.10±0.44g) were divided into 4 treatments i.e. treatment T1 T2, T3 and T4 having three replications each. The fish were fed twice a day with a standard feed (40% protein) having 4 doses of vitamin E viz. 0 (served as control), 50, 100 and 150mg vitamin E/kg feed. At the end of the feeding trial, the brood fish were induced to breed with PG extract to observe the effect of vitamin Eon feed. After rearing for 90 days with the experimental feeds, it was found that weight gain and specific growth rate of brood fish fed with 100mg vitamin E/kg feed (treatment T3) was the highest (14.78±0.38g and 2.99±0.11) while 150mg vitamin E/kg feed (treatment T4) fed fish gave the poorest result (2.97±0.89g and 1.21±0.32). There was no significant difference in terms of length gain of brood fish among the different treatments. The brood fish were induced to breed with equal dose of PG extract (18 and 12mg PG/kg body weight for female and male respectively) to observe the dietary effect of vitamin E on breeding performance. The highest ovulation, fertilization and hatching rate of eggs were found to be 81.48±6.41%, 84.04±3.53% and 68.59±5.03% respectively in the brood fish of treatment T1 while the poorest (33.33±00%, 52.35±5.02% and 45.70±7.24% respectively) were found in the brood fish under treatment T4. The results suggest that inclusion of 100mg vitamin E/kg feed is best for enhancing the breeding performance of O. pabda brood fish indicating that vitamin E content has a positive impact on reproduction of fish. The present results also imply that inclusion of higher level of vitamin E exerts an antagonistic effect in terms of growth and breeding performance of this species.

Genetic study on breeding stock of the Indian mackerel along the Indian coast

The study included: sample collection; microsatellite genotyping and analysis; and preliminary results