Effect of stocking density on the production of common carp (Cyprinus carpio Lin.) in cages at Kaptai lake, Bangladesh

Growth, survival and food conversion ratio (FCR) of Cyprinus carpio in cages at different stocking density were studied in Kaptai lake. Fingerlings of common carp (12.47 ± 4.29 g) were stocked at 25/m2 , 50/m2 and 75/m2 each with replication in six floating net cages each of Sm x Sm x 4m and reared for 240 days. The growth rate was inversely related to the stocking density with the mean weights of 325.5 ± 11.74 g, 268.99± 8.44 g and 167.0 ± 11.66 g at low, medium and high densities, respectively. At harvest, standing crop biomass averaged 7 .82, 12.83 and 11.58 kg with the survival of 98.9%, 97.6% and 94.4% and food conversion ratios of 4.51, 3.82 and 4.21 for the above three densities, respectively. Weight gain and production at density 25 fish/m 2 were significantly different (p< 0.01) from other two densities. Water quality was not affected in the cages having different stocking densities.

Euglenophytes in aquaculture ponds - their ecology and role in fish production

The ecology of euglenophytes and their role in fish production were studied in 12 small earthen ponds beside the Faculty of Fisheries, BAU from July to November 2001. Four experiments each with three replications were conducted and those were as follows: pond treated with both poultry droppings and cowdung (T1); pond treated with only poultry droppings (T2), and pond treated with only poultry droppings (T3), while the control (T4) where no organic manure was applied. Fishes comprising of rohu (Labeo rohita), catla ( Catla catla), mrigal ( Cirrhinus cirrhosus), silver carp (Hypophthalmichthys molitrix) and silver barb (Barbonymus gonionotus) were stocked at the same stocking density of (10,621 fish/ha) and species ratio (1:1:1:2:2). The stocked fishes were fed with a common supplemental diet comprising of mustard oil cake and rice polish (1:1) at the rate of 4% of body weight per day. The highest cell density of euglenophytes was found in the ponds of T2, where poultry droppings were applied and was followed by T1, where both poultry droppings and cow dung were applied. Higher temperature, nitrate-nitrogen, phosphate-phosphorous and acidic pH were found to be conducive for the bloom of noxious euglenophytes. The bloom was found to use up most of the nutrients resulting in reduction in the growth of beneficial plankters and planktivorous fishes. The SGR (%/day) of catla, rohu and mrigal was lower during heavy bloom period while that of silver carp and silver barb were comparatively higher. The mortality of fishes in a pond of T2 during the bloom period was possibly due to formation of anoxic situation (dissolved oxygen level as low as 0.34 mg/1) in the early mornings through bacterial decomposition of the settled dead individuals or due to the combined effect of anoxic situation and toxic metabolite secretion by the euglenophytes.

Seasonal fluctuation in primary production in relation to the physicochemical parameters of two weed-infested ponds of Kalyani, West Bengal

Kalyani lake (P sub(1)), a weed infested recreational water body and a weed chocked derelict water body (P sub(2)) in the heart of Kalyani city of West Bengal were studied for a period of one year for their primary productivity and other physicochemical parameters. Very low primary productivity (GPP=360-1237mg C m super(-2) d super(-1); NPP=157-787 mg C m super(-2) d super(-1)) was recorded in P sub(2) in spite of having a high concentration of nutrients (PO sub(4)–P=0.052-0.260mg l super(- 1); NO sub(3)-N=0.110-0.412mg l super(-1)). On the other hand, moderate primary productivity (GPP=1687-3195mg C m super(-2) d super(-1); NPP=900-2700mg C m super(-2) d super(-1)) was found in P sub(1) with comparatively low range of nutrients (P0 sub(4)-P =0.010-0.058mg l super(-1); NO sub(3)-N=0.032-0.118mg l super(-1)). After studying the other physicochemical parameters (temperature, transparency, dissolved oxygen, free carbon dioxide, pH, alkalinity and macrophytic biomass), it was found that the overall hydro-biological conditions of the weed-chocked derelict water body (P sub(2)) is not congenial for biological production as compared to Kalyani Lake (P sub(1)). Kalyani Lake may be used for fish culture with proper management practices.

Seed production and culture techniques of Genetically Improved Farmed Tilapia (GIFT) in brackishwater environment

Effects of different levels of salinity on survival, growth and gonadal development of Genetically Improved Farmed Tilapia (GIFT) were studied under laboratory conditions in glass aquarium, for a period of ten weeks. The initial individual size of the GIFT was 20.23±4.45 and the salinity levels tested were 0, 5, 10, 15 and 20 ppt. The highest survival of 87.5% was found in 0 ppt and the lowest 60.5% in 20 ppt. Though the survival decreased progressively with increased salinity, there were no significant differences (P>0.05) among 0, 5, and 10 ppt. Similar to what has been observed in survival, the specific growth rate (SGR %/day) also decreased as of 1.30, 1.24, 1.08, 0.90 and 0.71, respectively, with the increased salinity of 0, 5, 10, 15 and 20 ppt. The gonadal development was highest in 0 ppt with a GSI value of 3.75 and lowest of 2.01 in 20 ppt. In the second experiment, gonadal development and seed production performance of GIFT in brackishwater condition were investigated for a period of three months. Each of the three fine meshed hapas of 20 square meters made from nylon net was placed in a freshwater (0 ppt) and in a brackish water (10-15 ppt) pond of the Brackishwater Station (BS). GIFT of 65 g average weight from a single cohort were stocked into three hapas at a rate of 2 per m. The male vs female ratio was 1:3. The development of gonad was faster with the higher gonadosomatic index (GSI %) of 3.85 % in freshwater condition than that of 2.73 % in brackish water. Within three months of the study period, a total of 70,510 and 44,250 GIFT fry were produced respectively, in freshwater and brackishwater conditions. Finally under third experiment, a participatory on-farm trial was carried out to evaluate the production performance of GIFT in monoculture and in polyculture with silver barb in coastal freshwater pond conditions. Nine ponds were selected for three treatment combinations of GIFT monoculture (T1), GIFT and silver barb polyculture (T2), and silver barb monoculture (T3). The ponds have been stocked in April, 05 at a density of 25,000 fry per ha. Fishes were fed with rice bran at the rate of 6% bw per day. In one month culture period, GIFT attained an average weight of 16.27 g in monoculture and 17.23 g in polyculture, against an average stocking weight of 0.37 g. Silver barb reached an average weight of 16.62 g in polyculture with GIFT and 10.01 g in monoculture, against an average stocking weight of 3.79 g.

Production and economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds

The production of fish and net economic return in pangasiid catfish (Pangasius hypophthalmus) monoculture and polyculture with silver carp (Hypophthalmichthys molitrix) in farmers' ponds were assessed. The experiment was arranged in three treatments each with three replications. The ponds were stocked with 30,000 fishes per hectare. In treatment 1 (T1) pangasiid catfish only, in treatment 2 (T2) pangasiid catfish and silver carp at the ratio of 1:1, and in treatment 3 (T3) pangasiid catfish and silver carp at the ratio of 2:1 were stocked. At harvest, production of fish was found significantly (p<0.05) different among the treatments, highest in T1 and lowest in T2. Though the total biomass production and total economic return was significantly highest in T1 than in T2 and T3, the net economic return was lowest because of the required highest input costs especially for supplemental feed and fingerlings, resulted the highest cost per unit yield (CPY in Tk/kg) in T1. Highest cost for supplemental feed required in T1 was due to highest quantity of feed required for the highest number of pangasiid catfish stocked in that treatment. The findings of the present study suggest that though monoculture of pangasiid catfish give higher fish biomass production but polyculture with silver carp is environmentally good and economically profitable.

Sustainable livelihood approach of prawn production and marketing systems in Mymensingh, Bangladesh

An investigation was carried out in Phulpur upazila, Mymensingh to examine the current production practices of freshwater giant prawn, Macrobrachium rosenbergii and its marketing systems with sustainable livelihood approach. The livelihoods of a considerable number of rural poor are associated with prawn production in Phulpur upazila. Based on a sample of 50 farmers, about 94% farmers were found to culture prawn with fish in their ponds. Only 4% and 2% farmers were found to culture prawn-fish-dike crops and only prawn respectively. Prawn marketing is almost exclusively a preserve of the private sector where the livelihoods of a large number of people are associated with its distribution and marketing systems. The market chain from producers to consumers passes through a number of intermediaries. About 40% of the produced prawns are exported and the rest 60% are sold to local markets. The price of prawn depends on quality, size and weight. The average farm-gate price of prawn varied from Tk. 110 to 160/kg, whereas it's [sic] market price varied from Tk. 150 to 350/kg. Most of the farmers and traders have improved their socio-economic conditions through prawn farming and marketing activities. However, concerns arise about the long-term sustainability of prawn farming and marketing systems due to lack of technical knowledge of prawn farming, poor road and transport facilities, higher transport cost, poor supply of ice, lack of cash and credit facilities. It is therefore essential to provide institutional and organizational support and credit facilities for sustainable prawn production and marketing systems.

Effects of black Bengal goat manure on growth and production of Genetically Improved Farmed Tilapia (GIFT) starin [sic], Oreochromis niloticus

In a goat-tilapia integrated farming system, the effect of Black Bengal goat manure on the growth and production of Oreochromis niloticus was studied at the Freshwater Substation, Shantahar, Bogra for 4.5 months. The stocking density used in three treatments were, 200 goats and 15,000 GIFT strain/ha (T1); 300 goats and 15,000 GIFT strain/ha (T2); and only 15,000 GIFT strain/ha (T3). The initial individual total length and weight of stocked tilapia were 7.6 cm and 11.34 g, respectively. Twelve ponds each having an area of 40 square meters were used for this trail [sic]. On one side of each pond goat shed was constructed and the space allocated for each goat was 0.75 m x 1.5 m. Newly weaned black Bengal goats of average weight 8.45 kg was used in the trial. Every morning the goats manure was swiped out in ponds through the fixed opening of bamboo made floor of goat shed. Water depth of the ponds was maintained at 0.75 m. The highest fish production was in treatment 1 (1,750 kg/ha) followed by treatment 2 (1,455 kg/ha) and treatment 3 (621 kg/ha). The difference in individual goat weight was not significant (P>0.05) among treatments 1 and 2.

Seed production and culture techniques of climbing perch, Anabas testudineus

Six treatments each with 12 replications designed to optimize the dose of inducing agent PG to achieve fertilization and hatching success of climbing perch, Anabas testudineus were tested. The females were given single injection of 7-12 mg PG/kg body weight and the males were given 4 mg PG/kg body weight. Fertilization and hatching rate varied from 67±4.55% to 66±3.0% and 59±4.88% to 57±6.21% for the doses of 10, 11 and 12 mg PG/kg of body weight, respectively. The hormone dose had significant (P<0.05) effect on fertilization and hatching. Six mini shallow cisterns (570 cm x 105 cm) were used to investigate the efficacy of zooplankton and Artemia nauplii as feed for spawn rearing. Three-day old spawns were stocked in six mini shallow cisterns at a stocking density of 100 individuals/L of water. Two treatments each with three replications were used to develop culture technique of the climbing perch. In case of treatment-1, the spawns were fed with Artemia nauplii three times daily, while in treatment-2, zooplankton were used as feed in the same manner as in treatment-1. After 14 days of rearing, mean final weight of the fry of treatments-1 and 2 were 95.55±6.71 and 57.69±5.40 mg, respectively. In treatment-1, spawn fed with Artemia nauplii showed significantly (P<0.05) higher mean weight than the spawn fed with zooplankton (treatment 2).

Effect of low cost feed on the production of walking catfish, Clarias batrachus in farmer's ponds

A feeding trial was conducted for six months in farmer's ponds to assess the performance of BFRI formulated catfish feed on the growth and survival of Clarias batrachus (L.). Nine interested farmers and their ponds (size range: 10-15 dec) in the Barera union of Mymensingh Sadar were selected. The ponds were divided into 3 treatments each with 3 replications. Among the three treatment diets, two diets - traditional (F1) and BFRI formulated (F3) were prepared by using low cost agro-based locally available ingredients and the commercial diets was Saudi-Bangla Grower-1 (F2). The diets were designed as F1, F2 and F3 for traditional (20.40% protein), Commercial (31% protein) and BFRI formulated (30.44% protein) diets respectively. The fingerlings of catfish (7.3 g) were collected from local fish vendors and stocked at the rate of 100/dec. Feeding rates were adjusted by weight after fortnightly sampling of fish. Feeding rate were 10 and 8% of the total body weight respectively for 1st, 2nd month and 5% for the rest of the experimental period. The range of some selected water quality parameters were as follows: dissolved oxygen 4.0 - 7.4 mg/l, temperature 24.0°- 33.9°C, pH 6.8 - 8.00, and transparency 17.0 - 32.00 cm. Which showed suitability of the ponds for rearing fish. At the end of the experiment, significantly highest gain (p<0.05) in weight (1210.96% ±87) and lowest gain in weight (865.25% ±90) were observed in the group of fish fed on diets F3 and F1 respectively. However, no significant differences in growth (p>0.05) was observed in fish fed on commercial diet (F2) and BFRI formulated diet (F3). The FCR value ranged between 2.00 and 2.80 with the traditional diet (F1) showing significantly lower FCR. The total production of fish ranged between 1398.08 and 2145.34 kg/ha with F3 diet resulting in the highest production and net profit. A simple economic analysis showed that fish fed with BFRI formulated (F3) diet resulted in the highest net profit in farmer's pond.

Management of euglenophytes in aquaculture ponds for improvement of fish production

Four experiments each with three replications were conducted in 12 experimental ponds to control the euglenophytes bloom viz. treatment 1 (T1, covering of one third of the water surface by duckweed (Lemna minor); treatment 2 (T2), application of 123.5 kg lime/ha/month; treatment 3 (T3), use of both duckweed as in T1 and lime as in T2; treatment 4 (T4) was considered as control where neither duckweed nor lime was applied. Fishes comprising of rohu (Labeo rohita), catla (Catla catla), mrigal ( Cirrhinus cirrhosus), silver carp (Hypophthalmichthys molitrix) and silver barb (Barbonymus gonionotus) were stocked at the rate of 1080 fishes/ha with the species ratio of 8:4:6:9:13, respectively. The lowest cell density of euglenophytes was found in the ponds of T3 followed by T2, and T1. In the ponds of T3, euglenophytes bloom did not occur possibly due to alkaline pH, shade and nutrient absorption by duckweed. Thin bloom was observed in the ponds of T1 where pH was neutral or slightly alkaline. The grazing on euglenophytes by the silver carp and silver barb also had some contribution in controlling the bloom. Growth of fishes was comparatively higher in the ponds of T3 and T1, which might be due to better water quality and availability of adequate food while the lower fish growth as recorded from the ponds of T4 might be due to euglenophytes bloom. Thick bloom inhibited light penetration which hampered photosynthesis and growth of other phytoplankton that are the preferred food of planktivorous fishes. Mortality of fishes in ponds having euglenophytes bloom was possibly due to formation of anoxic situation in the early morning or due to the combined effect of anoxic situation and toxic metabolites secretion by the euglenophytes.

A review on oil sardine 2. Preservation by canning, curing and smoking

Commercial canning of oil sardine (Sardinella longiceps) in India is a relatively new procedure. Although 7 firms are engaged in canning this compares poorly with the abundance of the fish. There are often wide variations in the quality of the canned fish and important chemical and physical variations occur in the product once canned. A description of the canning process is given, and production figures compared to those of other countries. Production figures for 1965 to 1969 are given. These show that production increased from 1.2 to 1.5 million cans, but that there was a peak in 1967 when 3.2 million can s were produced. Exports of canned marine fish by country, and production of caned sardine by country from 1965 to 1970 are tabulated. The types of containers used and the feasibility of exporting canned fish are considered. Finally, the preparation of cured and smoked products is discussed briefly.

Pilot plant for production of fish ensilage and the economics of production

This communication describes the design aspect and functions of individual pieces of equipment of a pilot plant for the production of fish ensilage based on lactic acid fermentation process. Details about the equipment, process flow sheet and equipment layout of the pilot plant have been given. An attempt has been made to prepare an estimate of the cost of production of liquid ensilage and solid feed mix.

Nucleotide degradation and production of hypoxanthine in some Indian marine and freshwater fishes

Changes in nucleotides and production of hypoxanthine in rohu (Labeo rohita), mrigal (Cihhrina mrigala) and common carp (Cyprinus carpio) during storage at 2-4°C were examined. Differences were observed between common carp and others. Production of hypoxanthine in pomfret (Stromateus argenteus), cat fish (Arius macronotacanthus), shark (Scoliodon spp.), seer fish (Scomberomorus guttatus), ray fish (Dasyatis imbricata) and prawns (Parapenaeopsis stylifera) was examined during storage at 2-4°C and -28°C. At 2-4°C hypoxanthine increased regularly but at -28°C there was no increase during storage over 28 weeks.

Survey on the idle capacity of fish processing (freezing) plants in India - 2. East coast

The extent of idle capacity in the fish processing (freezing) plants in the east coast of India estimated by stratified random sampling and the factors responsible for the same are reported. The estimates of idle capacity of fish processing plants in the east coast for the years 1978 and 1979 were respectively 75.9% and 72.5% on the basis of 250 working days per annum and double shift per day. The percentage errors of estimates worked out to 6.9 for 1978 and 4.7 for 1979. The corresponding figures were worked out on the basis of 200 working days also. Substantial under-utilisation of plants in all the maritime states in the east coast accounted mainly to non-availability of raw material, high cost of production, shortage of power, scarcity of ice and potable water during peak season and frequent labour troubles.

Land-based mass production of prawn (Penaeus monodon Fabricius) spawners

The first spawnings were obtained 12 days after ablation with 4 spawners yielding 784,000 eggs and a harvest of 250,000 P SUB-10 fry. Survival of females after 1 month was approximately 30%. Mortalities were mostly due to handling stress during the regular ovarian samplings as well as disease frm the accumulated excess feeds on the bottom of the tank. Male survival could not be recorded because of transfers to other tanks and addition of new stocks. Development seemed to peak 3 weeks after ablation. The average number of eggs per ablated spawner was 120,000. However, many of the partially spawned females were removed from the spawning tanks the following day so that remaining eggs released in the next 2 to 3 days could not be recorded. Estimate of the average number of eggs per ablated spawner is 120,000-150,000 in contrast to 500,000 per wild spawner. However, the low production cost more than compensates for the difference. Fry reared in the Wet Laboratory were used for experiments, mostly on feeding. Therefore, survival at harvest is not to be taken as a reflection of stock quality. Although fewer in number, larvae from ablated prawns are as healthy in terms of vigor in swimming and feeding as those from wild females. Most mortalities are due to inability to molt caused by lower water temperatures and inadequate feeding.