Prawn culture and policy options: technology import and culture through fishermen vis a vis industry

Recent developments in aquaculture has created an awareness that prawn culture is a dollar spinner, in which industry can step in to earn foreign exchange by producing an expensive food iten which has a high market demand abroad. The Government has to take a policy decision whether the prawn culture should be done through small fishermen to improve their socio-economic condition or through private industry with the high technology input and predefined objectives of export trade. Perhaps a simultaneous operation of the two could be allowed best in the interest of India. Perhaps in the interest of quick development and adoption of high production technology, through fishermen organization, the development is encouraged through the implimentation of welfare and area development schemes. In some selected areas private industry may be encoureged to use high production technology to develop prawns.

Culture of Moina micrura on various organic waste products

Moina micrura, a cladoceran species, is considered to be one of the best live food organisms for rearing the young larval stages of fish and prawn. Considering the importance of this species in hatchery operations the present study was undertaken to record its fecundity and life span and to culture it using different locally available organic waste products. In indoor culture, a maximum production of 2600 ind/1 and a minimum of 1050 ind/1 were obtained when treated with gram + maize oilcake and "till" oilcake respectively. In outdoor culture, a highest production of 6000 ind/1 was achieved with "Alsi" and "till" oilcakes and a lowest density of 1050 ind/1 with coconut oilcake and raw cattle dung was obtained with an inoculation rate of 5 ind/1.

Prospects of integration of aquaculture with animal husbandry and land crop culture in Tripura State

Tripura is a densely populated small state with meagre water resources. 47.51% of the population is constituted by socio-economically backward, illiterate, orthodox, tribal and scheduled castes. Some of them are nomad and a majority of the rest of the population is refugees from Bangladesh, but almost 100% is fish eater. Settlement of tribes in villages, provision of nutritious food and employment therefore calls for proper utilization of every resource they have. The State is poor in water resources but recently has created 21,636.23 ha of new water area. Tripura is rich in pig population, besides poultry birds. Paddy is the main crop cultivated in arable lands. An integration of livestock raising and land based agriculture with pisciculture practices around mini barrages will help in solving the problems to a great extent. The paper is an attempt to outline the prospects of integration of aquaculture with animal husbandry and land based crop culture in Tripura State.

Influence of stocking density on the culture potential of freshwater catfish Pangasius pangasius in pond

Influence of stocking density on the production of freshwater catfish Pangasius pangasius with formulated feed in ponds was studied. The fish fry were collected from the Meghna river near Chandpur which is a natural breeding ground of this fish. Three stocking densities chosen during this experiment were 5000, 8000 and 11000 fry/ha with an initial weight of 42.57 ±2.51 g. The formulated feed was prepared in the laboratory which contained 45% fish meal, 30% mustard oil cake, 15% wheat bran and 10% rice bran to supply 40.48% protein in feed. The growth of P. pangasius in terms of net weight gain was 409.49, 266.49 and 236.37 g at the 5000/ha, 8000/ha and 11000/ha stocking densities respectively, which was statistically significant (p<0.05). High food conversion ratio (FCR) was also observed during this research study which ranged between 7.06 to 7.72. A production of 2.6 tons/ha at the stocking density of 11000/ha; 2.13 tons/ha at the stocking density of 8000/ha and 2.04 tons/ha at the stocking density of 5000/ha was obtained, while the growth of individual fish at the end of experiment was in opposite order. The result of this experiment indicates that stocking density has significant influence on the culture potential of freshwater catfish P.pangasius.

Culture potentials of bata, Labeo bata under semi-intensive management system

Small indigenous fish species (SIS) provide food, nutrition, subsistence and supplemental income to a great majority of the people particularly the poor and disadvantaged people of Bangladesh. To date nobody explored the possibilities of culturing these species in combination with the indigenous major carps viz. catla, Catla catla; rohu, Labeo rohita, and mrigal Cirrhinus cirrhosus and grass carp, Ctenopharyngodon idellus. An experiment on the polyculture of carps with a popular SIS, bata (Labeo bata) was carried out to evaluate the production performance of carp-SIS culture in on-farm condition during 15 March to 15 September 2003. Three treatments each having three replications with different stocking densities of bata were tested keeping the carp species combination and stocking density similar in all the treatments viz. treatment 1 (T1), bata (5,000/ha) + catla, rohu and mrigal (5,000/ha at the ratio of 1:1:1) + grass carp (250/ha); treatment 2 (T2), bata (7,500/ha) + catla, rohu and mrigal (5,000/ha at the ratio of 1:1:1) + grass carp (250/ha); and treatment 3 (T3), bata (1 0,000/ha) + catla, rohu and mrigal (5,000/ha at the ratio of 1:1:1) + grass carp (250/ha). After six months rearing, the production obtained were 2,466±77, 2,395±85 and 2,074±72 kg/ha from T1, T2 and T3, respectively. The highest production was obtained from T1, where the stocking density of bata was the minimum (5,000/ha) while the lowest production was obtained from T1 [sic], where the stocking density of bata was maximum (10,000/ha). Significant difference (P<0.05) exists in the production levels as obtained from different treatments. The contribution of bata to total production was 10.31%, 13.96% and 14.38% in case of T1, T2 and T3, respectively.

Hydrobiological studies of an irrigation tank with reference to the culture of large murrel, Channa marulius (Hamilton) and striped murrel Channa striatus (Bloch)

The importance of selection of species for culture according to the ecological niches and fish food organisms is highlighted with respect to the Fox Sagar, an irrigation take. The tank was infested with submerged vegetation as well as minnows and weed fishes, which rendered the tank unsuitable for the culture of Indian major carps. The tank was stocked with 8000 fingerlings of Channa marulius and C. striatus during 1981 by the local fisherman co-operative society. Only partial harvest was possible during 1982 because of high water level. The final harvest was in April-May, 1983. The yield obtained was 3640 kg during the culture period of about 20 months.

Identification and culture of common diatoms as possible feed for Penaeus monodon

Diatoms were collected from Buyuan Bay, and from the hatchery tanks at Tigbauan, to determine the commonly occurring species, the feasibility of culturing these species, and the potential of these selected species as food for larval P. monodon. The commonly occurring diatoms were identified as Chaetoceros calcitrans, Navicula grimmei, Nitzchia seriata, Nitzchia closterium and Amphiprora sp. These diatoms were isolated and unialgal cultures prepared. Protein content analysis using the micro-Kjildahl method gave the following result: C. calcitrans, 11 . 78%; Nitzchia seriata, 25%; Nitzchia closterium, 30 . 5%; Navicula grimmei, 9 . 06% and Amphiprora sp. 8 . 96%. Feeding experiments were conducted to determine acceptability of the different diatom species and percentage survival of larval stages Z SUB-1 -M SUB-2 . Larvae were placed in 4-l capacity plastic containers with a stocking density of 10/l. The results of several feeding trials using the different mass-produced diatoms are summarized. From the data gathered, C. calcitrans appears to be the most promising candidate as feed for zoea and mysis stages of P. monodon. The average percentage survival of C. calcitrans was 63 . 76% for the 3 trials, and as high as 82 . 22% in the third trial. Comparatively high percentage survival of larvae was also recorded when Nitzchia seriata (48 . 17%) and Nitzchia closterium (67 . 6%) were given as feed, while both Amphiprora sp. and Navicula grimmei gave 0% survival. The poor results with Amphiprora sp. and Navicula grimmei may be due to their low protein content (8 . 96% and 9 . 06%, respectively) and the inability of the larvae to ingest them. Navicula and Amphiprora were observed to cling to the appendages of the larvae and to settle down in the medium making them unavailable to the larvae. Low survival was also noted when frozen C. calcitrans was used (14 . 25%). This may be due partly to the effect of the floculating agent (ALSO SUB-4 . 25 g/l) used in concentrating the diatoms. When protein contents of C. calcitrans, N. seriata and N. closterium are compared, the 2 Nitzchia species have relatively higher protein contents than C. calcitrans and, therefore, could be the more desirable feed candidates. However, few feeding trials were made using Nitzchia so that additional investigations will have to be done on this aspect.

Organic pollution in culture water resulting from excess feed and metabolite buildup

Penaeus monodon postlarvae were subjected to increasing feed concentrations and their growth and survival rates were recorded. Measurements were made of dissolved organic matter, and ammonia and nitrite-nitrogen concentrations. Survival was highest at the lowest feeding level and decreased as feed concentration increased. It is concluded that although organic matter enriches the food supply for P. monodon postlarvae, at higher concentration levels it can pollute the culture water, which in turn leads to mass mortality of the postlarvae. Secondly, the survival rate of P. monodon postlarvae is directly related to dissolved organic matter concentration, oxygen tension, and ammonia-nitrogen concentrations in the culture water. Even at sublethal levels these adverse environmental conditions decrease the survival rate.

Effect of two green algae species (Chlorella sp. & Scenedesmus obliquus) enriched with B group vitamins on food chain of Rutilus frisii kutum (Kamensky, 1901) fry

The Effect of two freshwater green algae species Chlorella sp. & Scenedesmus obliquus enriched (from the beginning of culture and after 96 hours) with different dosages of B group vitamins (0, 0.5, 1, and 2 ml of enriching solution per each liter of algae medium) on fecundity of Daphnia magna and growth of Rutilus frisii kutum fry were investigated in a research from spring, 2008 to autumn, 2009. First, each of the green algae species were cultured purely and massively in the Zander (Z-8+N) medium and then the nutritional value (the amount of protein, lipid, and carbohydrate) of enriched algae were meausered. In this study, enriching of Chlorella sp. & S. obliquus with a suitable mix of B group vitamins significantly improved their nutritive value. So the highest amount of nutritional value of Chlorella sp. was obtained because of enriching with dosage 0.5 ml.l-1 (366.654Kcal) and for Scenedesmus obliquus with dosage of 1 ml.l-1 (376.95Kcal). The acquired amount from control group showed an increase of respectively 42% and 11%. According to the results, increased dosages of enriching solution caused Daphnia fecundity to increase (at both stages : enrichment from the beginning of culture and after 96 hours). So the highest average of D. magna reproduction rate was obtained through being fed with Chlorella sp. and S. obliquus enriched with dosage of 2 ml enriching solution per liter of algae medium. The average fecundity of D. magna fed with Chlorella sp. enriched with dosage of 2 ml.l-1 enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 and the average fecundity of D. magna fed with S. obliquus enriched with dosage of 2 ml enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 which showed respectively an increase of 61 ٪, 91٪, 77 ٪, and 83٪ in proportion to the acquired amount from control group. When enriching solution was added to either algae culture medium from the beginning of culture, showed statistically significant differences (P<0.05) between dosages of 0 and 2 ml.l-1, 1 and 2 ml.l-1, and 0.5 and 2 ml enriching solution per each liter of Chlorella sp. culture medium and between dosages of 0 and 1 ml.l-1, and 0 and 2 ml enriching solution per each liter of S. obliquus culture medium. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 21.19%, 26.63%, 1.92, and 2.34 from the beginning of culture and after 96 hours with dosage of 1 ml B group vitamins per each liter of Chlorella sp. culture medium, which showed respectively an increase of 50%, 70%, 46%, and 62% in proportion to the acquired amount from control group. In the cases which Chlorella sp. were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 1 and 2 , 0.5 and 1 ml B group vitamins per each liter. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 32.02%, 29.42%, 2.78, and 2.34 from the beginning of culture and after 96 hours with dosage of 2 ml B group vitamins per each liter of S. obliquus culture medium, which showed respectively an increase of 32%, 19%, 28%, and 17% in proportion to the acquired amount from control group. In the cases which S. obliquus were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 0 and 2. According to the results of the present research we can say that considerable enhancement in the quality of the food of D. magna can be made by manipulation of the nutritional value of fresh water unicellular green algae with suitable mixture of B group vitamins, so that both the fecundity of D. magna will increase and the nutritional requirements of the kutum fry will be filled in this way.

Food preference in the cultured species, Penaeus monodon Fabricius (Crustacea: Decapoda)

The study of food preference is necessitated by the need to promote coastal culture of shrimps in Pakistan. The cultured Penaeus monodon was selected for study. Food preferences have been examined through the analysis of the gut contents. The shrimp shows a seasonal variation in its preference to food and feeding.

Development of cell culture from caudal fin and heart of Tor tor (Hamilton-Buchanan)

Tor mahseer (Tor tor), possess high commercial and recreational value as they are potential game as well as food fish of India. Two cell culture systems were developed from fin and heart of T. tor (Hamilton-Buchanan). The explants excised aseptically from fingerling of T. tor were cultured in Leibovitz-15 (L-15) medium with 20% fetal bovine serum (FBS). Radiation of cells started after 72 hours and 48 hours of explant attachment from caudal fin and heart respectively. Confluent monolayer of cells with heterogeneous morphology around fin explants was observed after 7-10 days, where as a homogenous confluent layer of fibroblastic cells from heart explant was observed after 12-13 days. The establishment of cell culture systems from different organs and tissues of commercial important species would facilitates in vitro research.

Preliminary observations on cage culture of Tilapia esculenta Graham and Tilapia xillii (Gervais) in Lake Victoria waters, at the Freshwater Fisheries Institute, Nyegezi, Tanzania

Cage culture of Tilapia is not suggested as a substitute for any known techniques in fish culture, but as one of the various techniques of obtaining more fish under controlled conditions. This fact has been very well accepted in various countries. Whererever facilities exist, this line of fish culture should be vigorously explored as a possible avenue in increasing fish production. High density stocking, management under controlled conditions, easy technique of fabricating the cage at relatively low cost, having no demand on land area, absence of prolific and effective breeding and easy availability of fish when a person needs it are a few of the attractions of the technique. The studies indicate that it is desirable to have different meshes for the cages, such as, small meshed cages for rearing fry to fingerlings stages, and larger meshed cages for rearing fingerlings to table sized fishes. II' the meshes are small, the resistance will be more and less water wilt pass through. While feeding with powdered food material, because of brisk activity of feeding fish, a part of the feed appeared wasted. This can be easily overcome if we would resort to feeding fish with cheap pelleted feeds which will no doubt reduce wastage. Precaution has to be taken against damage of the net and thereby loss of fish and against poaching by unauthorised persons. In the present attempt has been demonstrated the possibility of utilizing locally available species of Tilapia for cage culture and obtaining moderately satisfactory growth rates.