Use of dopamine antagonists on induced spawning of Indian major carps

To test the efficacy of the technique of using dopamine-antagonists with pituitary extracts, experiments were conducted in July/August '93, at the CIFE Fresh water Fish Farm, Powerkheda. In all, 35 sets (1 female x 2 male in each set) were tried individually. 19 sets were treated with Domperidone (DOM) and Carp Pituitary Extract (CPE) and they constituted the experimental sets, while the rest 16 were treated with CPE and formed the control sets. The breeding, complete ovulation and hatching was 84.2%, 87.5% and 85.7%, respectively in the experimental sets whereas it was 93.7%, 60% and 72.7%, respectively in case of control sets. Experimental sets yielded 1.20 lakh spawn/kg body wt. (female) as compared to 0.83 lakh spawn kg body wt. (female) received from control sets on average basis. When DOM was used at 50-60% there was 100% breeding success but when increased to 70%, breeding rate fell to 66%. In mass breeding of Catla in the circular hatchery DOM mixed with CPE in 50:50 ratio gave excellent results.

Effect of Lates calcarifer seed stocking on the survival and production of Indian major carps reared in a freshwater coastal pond in Konkan region

The experiment indicated feasibility of culturing Indian major carps seed with Lates calcarifer, if the size of Indian major carps is larger. In the present investigation the average growths of Catla catla, Labeo rohita and Cirrhinus mrigala are recorded as 1193, 1120 and 821 g, respectively, during the year 1997-98, 1998-99 and 1999-2000 in 7.5 months. Complete harvesting of L. calcarifer is essential before stocking of new seed. The average growth of L. calcarifer was recorded as about 670 g during the above period. About 5000 numbers of Indian major carps fry per hectare can be stocked under the present culture system

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.

Polyculture of giant freshwater prawn, Macrobrachium rosenbergii, with Indian major carps: a case study

A study conducted in a 450 m² earthen pond to evaluate the production potential of giant freshwater prawn (stocked at 20,000 juveniles/ha) and Indian major carps, catla and rohu (stocked at 5000 juveniles/ha in 2:1 proportion) revealed that in nine months growing period, catla and rohu attained average sizes of 357 and 746 g, respectively, while prawn weighed 48.32 g. The growth of rohu was much faster than catla as indicated by higher relative and absolute weight gains. The total fish production per hectare was estimated to be 2418 kg and prawn production stood at 780 kg with excellent survival of both the fish (>98%) and prawn (>80%).

A note on application of hills procedure for growth-curve analysis of Indian major carp, Labeo rohita (Ham.), during the gonodal development period at Shillong, Meghalaya

The present study deals with the length increment data of 15 adult Labeo rohita (Ham.) over a period of five months by the applicatin of finite difference method at an altitude of 1496 m above mean sea level at Shilllong, Meghalaya.

Characterization of the fisheries of the major and minor lakes of Uganda and the socio-economic factors influencing fishery exploitation

There is growing recognition that the performance of the fisheries sector depends on the communities responsible for activities within it. These communities include fishers, processors, fish mongers, traders, local leaders, fishery administrators etc. On the basis of this, characterisation and diagnostic studies were conducted in 1995 focussing on mainly the fishers and opinion leaders on the major and some minor water bodies in Uganda. The study revealed that the desire to earn income is the driving force behind the malfishing practices experienced on Uganda fisheries. The destructive fishing gears and fishing methods as responses advanced by the fishers and opinion leaders were seines and cast nets on lakes Victoria, Kyoga and Albert and to a less extent traps

Induced spawning of two major species of Chinese carps, Ctenopharyngodon idellus and Aristychthys nobilis in Sri Lanka

Induced spawning of grass carp (Ctenopharyngodon idellus) and bighead carp (Aristychthys nobilis) was carried out successfully in Sri Lanka for the first time in 1977 and 1978, respectively. This article describes the techniques involved in induced spawning in Sri Lanka at the Freshwater Fish Breeding and Experimental Station in Udawalawa.

Major histocompatibility complex class I involvement in the rejection of allogeneic erythrocytes in rainbow trout (Oncorhynchus mykiss)

Major histocompatibility complex genes are thought to be involved in allogeneic graft rejection but not many reports are available on their functional analysis in fish. Analysis of available sequences of MHC genes suggests functions in antigen presentation similar to those found in higher vertebrates. In mammals, the MHC class I and class II molecules are major determinants of allogeneic graft rejection due to their polymorphism in conjunction with their antigen presenting function. In fish, MHC class H molecules are found to be involved in rejection of allogeneic scale grafts. The present study was designed to investigate the involvement of MHC class I molecules in allograft rejection. Erythrocytes were collected from donors of rainbow trout expressed different class MHC class I alleles, stained with two dyes, mixed and grafted to the recipients that were of the same sibling group as the donors. The grafts were rejected by allogeneic recipients and the MHC class I linkage group was the major determinant for the rejection.

Bacterial load in pond water and different organs of a Indian major carp Cirrhinus mrigala Ham.

During the study period (August, 1993 to July,l994) the mean bacterial load in surface water was found to vary from 1.39 xl05 (July'94) to 3.llxl07CFU/ml (September'93), while that of botrom water ranged from l.Olxl06 (May'94) to 5.90xl07CFU/ml (October '93). The mean total number of bacterial load in body slime, liver and kidney was found to vary from 0.58xl03 (July'94) to 2.37xl07CFU/g (March'94),from 0.22xl03(July'94)to 9.64xl06 CFU/g (March'94) from O.l5xl03 (July'94) to 9.36xl06 CFU/g (March'94), respectively. Bacterial load in slime was significantly correlated with bacterial load in liver, bacterial load in slime was significantly correlated with bacterial load in kidney and bacterial load in liver was significantly correlated with bacterial load in kidney.

Monogenean gill parasites of Indian major carps from different fish farms of Mymensingh, Bangladesh

All together 148 fish host samples of Labeo rohira, Cirrhina mrigala, Catla catla and Labeo gonius were collected from different fish farms of Mymensingh. The gill monogeneans were then dislodged from the gill under dissecting microscope and fixed in ammonium picrate. Five species of Dactylogyrus namely, Dactylogyrus mrigali, D. chauhanus, D. yogendrai, D. labei and D. kalyanensis were recovered from sampled fishes. All the parasites were studied and redescribed, and reported for the first time from Bangladesh. The present investigation established Catla catla as a new host of D. labei.

Sperm cryopreservation of Indian major carp, Labeo rohita: cryodiluents, sperm: cryodiluent dilution ratio and cryoprotectan t concentration

Cryogenic preservation trials of spermatozoa of Labeo rohita were carried out. Twenty four cryodiluents (extender + cryoprotectant), with the combination of six extenders such as egg-yolk citrate, urea-egg-yolk, 0.9% NaCl, Kurokura-2, Ma and Mb and four cryoprotectants viz. DMSO, glycerol, methanol and ethanol, were used to screen out the suitable cryodiluents. Sperm was preserved in 0.25ml plastic straw in programmable freezer. Two step freezing method was followed. Sperm preserved with egg-yolk citrate and urea-egg-yolk containing 10% DMSO showed best post-thaw motility (80%) followed by 0.9% NaCl (60%) and Kurokura-2(30%) solutions. Sperm with the extenders M" and Mb clotted at the time of equilibration and also after few days of preservation. Egg-yolk citrate mixed with ethanol and methanol also showed good percentage of motility (80%) but egg-yolk citrate with glycerol showed less sperm motility (>60%). To determine suitable dilution ratio of milt and cryodiluent two best extender eggyolk citrate and urea-egg-yolk with four cryoprotectants such as DMSO, glycerol, methanol and ethanol at different ratio viz 1:2,1:4,1:7,1:10,1:15 and 1:20 were used. Highest post-thaw motility (>80%) was observed when milt was preserved with egg-yolk citrate containing 10% DMSO at 1:2, 1:4, 1:7 and 1:10 dilutions. Meanwhile using glycerol as cryoprotectants provided less post thaw motility at lower dilution ratio but with the increase of its dilution showed good sperm motility compared with other cryoprotectants. Finally, evaluation on the effect of cryoprotectant concentration on post-thaw sperm motility was conducted. Egg-yolk citrate and four cryoprotectant i.e. DMSO, glycerol, methanol and ethanol with six different concentrations namely 5%,7%, 10%, 15%, 20% and 30%.were evaluated. Among the cryoprotectants DMSO, methanol and ethanol showed highest post-thaw motility (about 80%) at 7% and 10% concentrations. Although glycerol was not suitable at low concentration but its 20% and 30% concentration levels provided best post-thaw motility. No post-thaw motility was obtained with DMSO at 30% concentration. The overall analysis on cryoprotectant concentration indicated that below 5% and above 20% cryoprotectant concentrations could not be suitable for effective cryopreservation of spermatozoa.

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.

Development of canned products from Indian major carp, catla (Catla catla)

Pieces of catla fish (Catla catla, a major carp of lndian subcontinent) of length 10 to 11 cm and thickness 1.0 to 1.5cm were precooked by two methods; steam precooking and frying. The precooked pieces were packed_in No.1 tall can (30lx411) with various hot filling media like oil, brine, tomato sauce and curry. Cans were seamed by a hand seamer and retorted at 117.2° C (12 psi) for 90 minutes. All the canned products had satisfactory cut-out, biochemical and organoleptic characteristics. Steam precooked canned products had moisture content of 65.6 to 74%, protein content of 20.8 to 22%, fat content of 1.1 to 6.6% and ash content of 2.1 to 2.5%; whereas fried canned products had moisture content of 65.4 to 68.2%, protein content of 21.3 to 22%, fat content of 7 to 10.2% and ash content of 2.1 to 2.7% on wet wt. basis. Salt content in steam precooked and fried canned products varied from 1.2 to 1.9% and 2.0 to 2.5% respectively. All the canned products were organoleptically good. However, degree of preference varied for different products. Canned fried catla in curry was the best product among all types of packs. Among the precooking methods, frying was more efficient than steam precooking in controlling the amount of exudate to a desirable limit in canned products. However, crispness, the characteristic quality for a fried fish, was lost during retorting. There was no change in quality characteristics during a storage period of 3 months at ambient temperature (32±2°C).

Influence of formulated diets with varying protein levels on growth and ammonia excretion in the fry of Indian major carp, Cirrhina mrigala

The influence of formulated isocaloric diets of different protein levels (30, 35, 40, 45 and 50%) on the growth and ammonia excretion of the Indian major carp Cirrhina mrigala fry was studied for a rearing period of four weeks in the laboratory. Fishmeal, groundnut oilcake and silkworm pupae formed the source of protein in all the diets. As the dietary protein level increased from 30 to 40%, the growth and conversion efficiency increased significantly. Further increase in the protein level resulted in decrease in growth and conversion efficiency. Growth rate, weight gain (%), and gross and net feed conversion efficiencies were maximum at 40% dietary protein level. Ammonia excretion was directly proportional to the level of protein in the diet.

Recovery, growth and carcass composition following periods of restricted ration and full feeding in indian major carp, Rohu (Labeo rohita H.)

A 90-day experiment was conducted to determine the effect of restricted ration and full feeding on the recovery growth and carcass compositions of fingerlings (average weight - 20.74 ± 0.13 g) of rohu, Labeo rohita (H.). Rohu fingerlings procured from a local fish breeder were fed with commercial pelleted feed (27% crude protein) during the two-week acclimatization in the laboratory condition. Experimental pelleted diet (30% crude protein) was prepared and the control group (T sub(CFR)) was fed at 3% of body weight for the 90-day trial period. The experimental group T sub(1FR) was fed for three days at 1% of body weight and the next three days at 3% of body weight, T sub(2FR) was fed for seven days at 1% of body weight and the next seven days at 3% of body weight, T sub(3FR) was fed for 15 days at l% of body weight and the 15 days at 3% of body weight and T sub(4FR) was fed for 25 days at 1% of body weight and the next 25 days at 3% of body weight, alternating between 1 and 3% for the specified period during the 90-day trial period. Daily rations were divided into two equal meals per day at 09.00 and 16.00 hours. Average percent survival rate of rohu during the 90-day trial period was more than 90. Percent live weight gain (98.90 ± 0.34, 113.0 ± 5.93, 125.71 ± 11.01 and 141.90 ± 2.89), specific growth rate (1.53 ± 0.01 1.68 ± 0.06, 1.80 ± 0.10 and 1.96 ± 0.02%/d) and absolute growth rate (1.33 ± 0.13, 1.38 ± 0.07, 1.39 ± 0.04 and 1.44 ± 0.07g/d) of the experimental groups (T sub(1FR), T sub(2FR), T sub(3FR) and T sub(4FR) respectively) increased with the advancement of the experiment in comparison to those in control, T sub(CFR) (90.92 ± 5.81%, 1.44 ± 0.07%/d and 1.34 ± 0.20g/d, respectively) and were proportionately correlated with the degree of deprivation probably through the mechanism of increased feed intake (hyperphagia), feed efficiency ratio or gross growth efficiency, protein efficiency ratio and the superior feed conversion ratio reflecting in better performance index. The body length and muscle composition of fish indicated that recovery growth happened due to protein growth but certainly not due to fat deposition in the gut. Feeding at 1 and 3% of body weight alternating over a period of 25 days might economize the culture operation of rohu.