Culture feasibility of african catfish (Clarias gariepinus Lin.) fry in glass tank and synthetic hapa system using supplemental diets

An experiment was carried out with 1 0 days old Clarias gariepinus fry over a period of 42 days to determine the effects of different feeds on growth and survival of African catfish fry in glass tanks. The experiment was designed into four treatments each having three replications. Thus treatment 1 (T1) was named as Tank Tubifex (TT) and treatment 2 (T2) as Tank Sabinco (TS), treatment 3 as Pond Tubifex (PT), and treatment 4 (T4) as Pond Sabinco (PS). Live Tubifex (protein levels 64.48%) was supplied to treatments 1 and 3 and rest of the treatments were supplied Sabinco starter-1 (protein levels 40.13%). The highest and the lowest growth in total length and weight were 12.90cm, 18.77g and 6.17cm, 4.04g recorded from the treatments 3 and 2, respectively. Growth of catfish fry under treatment 3 in terms of both length and weight were significantly higher (P<0.01) than those of the other treatments. However treatment 2 showed the significantly lowest (P<0.01) growth performance among the various treatments. The highest survival rate (92%) was also obtained with treatment 3. Tubifex proved to be the best larval feed in respect of growth and survival rate.

Effects of testosterone propionate on growth, survival and sex-ratio of African catfish (Clarias gariepinus Burchell)

For studying the effects of different levels of testosterone propionate on growth, survival and sex-ratio, five different doses such as 125, 100, 75, 50, 25 mg hormone per kg feed were administered to 5-day old Clarias gariepinus fry through diet for a period of 40 days. The growth performance in terms of weight and length gain of the fry receiving 100 and 75 mg hormone per kg feed were significantly higher than those receiving 50, 25 and 0 (untreated control) mg hormone per kg feed. The groups of fry treated with higher doses of hormone showed lower survival compared to those with lower doses of hormone. The frequency of male fish in the entire hormone treated groups except the 125mg/kg group, was significantly higher than that of the expected frequency of male fish in a normal population. The highest frequency of male fish, 92.08%, was obtained with the diet containing 50 mg hormone/kg diet however, the highest levels of hormone (125mg/kg diet) resulted in relatively lower frequency of male fish.

Studies on the optimum protein to energy ratio of African catfish (Clarias batrachus Burchell)

A laboratory trial was conducted to determine the optimum dietary protein to energy (P/E) ratio of African catfish, Clarias gariepinus. The experiment was carried out in a flow-through system for 6 weeks. There were 12 treatments each with two replicates having 10 fish each with a mean initial weight of 1.80 ± 0.02g. Twelve semi-purified diets were formulated with four digestible crude protein levels (23, 26.5, 30 and 33.5%) and three digestible energy levels (2.25, 2.75 and 3.25 Kcal/g). The fish were fed three times daily at satiation level. The results of the study showed that, diet containing 33.5% digestible protein and 2.75 kcal/g digestible energy with a protein to energy ratio of 121 .8 (mg protein/kcal) appeared to be best utilized for growth.

Minimization of cannibalism of African catfish (Clarias gariepinus Burchell) larvae in indoor culture system

For minimizing cannibalism of African catfish (Clarias gariepinus) larvae two trials for a period of 14 and 15 days respectively in four aquaria of size 120x49x32 cm³ were conducted. Seven days old African catfish larvae with an initial total length and weight of 7.84 (±0.40) mm and 4.40 (±1.18) mg respectively in the first trial and similarly 7.52(±0.61) mm and 3.98 (±0.56) mg in the second trial at the rate of same stocking densities of 2500 larvae in each aquarium were stocked in both trials. Cannibalistic larvae were separated by using grader frame from each treatment at 7 days and 5 days interval during first and second trial respectively. Two mesh sizes i.e., 5 mm and 7 mm were used in the grader frame in both trials. Survival rate was significantly higher in T1 than that of T2 in each trial. Grading of larvae with 5 days interval resulted higher survival rate than that of 7 days interval.

Incidence of ulcer disease in African catfish (Clarias gariepinus Burchell) and trial for its chemotherapy

Young Clarias gariepinus cultured in an artificial tank were severely affected by an ulcer type of disease where 77% fish died within 5 weeks. From the lesions and kidney of affected fish Aeromonas, Pseudomonas, Flavobacterium, Micrococcus and Staphylococcus were isolated where Aeromonas was observed as the dominant bacteria. Among them, an A. hydrophila isolate AGK 34 was detected as a pathogen by the experimental challenge test. In order to find out a suitable remedial measure of the disease, four different chemotherapeutants were applied to the affected fish in 6 different ways under laboratory condition. Affected fish were recovered from the disease in different treatments. But the best result was obtained by a successive bath in 1-2% NaCl and subsequent oral treatment with commercial oxytetracycline at a dose of 75 mg/kg body weight of fish.

Effect of different feeds on growth, survival and production of African catfish (Clarias gariepinus Burchell)

An experiment was conducted to study the effect of different feeds on growth survival and production of African catfish (C. gariepinus) in six cemented tanks (3m² each) over a period of 120 days. Three different feeds namely Feed A (Saudi-Bangla fish feed, 33.43% protein), Feed B (formulated feed, 40.12% protein) and Feed C (chicken raw intestine, 59.58% protein) were applied to treatments I, II and III respectively. Each of the tanks was stocked with 24 fry with mean initial body weight of 2.56±0.06 g. Feeds were supplied to the fish ad-libitum daily in two instalments. Significantly highest weight gain was obtained in treatment III, however, survival rate was low compared to other treatments. The feed conversion ratio (FCR) values ranged from 2.52-6.4. Survival rate of fish varied between 83 and 96%. Treatment II yielded the highest (5000 kg/ha/120 days) production with the highest survival rate of fish. On the basis of survival rate and production, it is suggested that the formulated feed (Feed B) is suitable for the culture of C. gariepinus in cemented tanks.

Lake Victoria Region (East) Annual Report 1976

The fishing industry on Lake Victoria continued to provide a wide spectrum of activities to a variety of people principally the fishermen and the fish mongers, boat builders,fishnets and associated equipment manufacturer transporters on land and water and finally the consumers of the end product the fish. Though there were such varied activities in the industry the year under review, as in previous other recent years, was difficult one being, characterized by continued shortages of fishing gear and accessories, spare parts for the outboard engines, timber for boat building, nails, paints and generally high prices of those items when ever found. Thus this total sum the activities of the fishing industry on Lake victoria was rather slack as compared to those of precious year.

Investigations on the bottom conditions and the possibilities for marine prawn and fish trawling on the north and east coast of Ceylon

The execution of this survey was decided upon by Swedevelop in agreement with the Sri Lanka Fisheries Corporation and was a part of the investigations and studies for a fishery project at Trincomalee which was carried out by Scandia Consult. The main purpose was to investigate the following aspects: bottom conditions, especially prawn trawling conditions; size of the potential prawn trawling catches; size and quality of the potential fish trawling catches; suitable sizes and types of boats and trawling gear; duration of trawl fishing season.

Vertical temperature structure of 250 m. water layer around Sri Lanka at the tail-end of the north-east monsoon

Data collected during cruises of the Hoyo Maru in Jan-Mar 1975 are analysed. Data is tabulated to show vertical temp profile, surface water temp and temp gradient. Each of these features is discussed. Thermoclines are shown to be established off the coast of India, their depth varying according to time of year. Upwelling off the Cochin coast is discussed. This occurs during Oct-Nov. Surface temp is considerably influenced by the north-east monsoon. The 'clockwise current' (or 'transparent current) characterised by high salinity, high transparency, and rich nutrient conchs, and which prevails in Jan-May brings oceanic water into the Bay of Bengal and sweeps along the Ceylon coast.

Reservoir fishery resources of south-east Asia

Although the reservoir area in south-east Asia is considerable, the fish production is low in the majority of reservoirs. Although high fish production has been recorded in a number of reservoirs in Sri Lanka and Indonesia, high fish production in reservoirs has with few exceptions resulted from the introduction of typical lake species from Africa. Addition of further lake fish species especially into deeper reservoirs will probably increase present fish yields. Diversification of the lake fish fauna can be achieved by introduction of species indigenous to the region like Etroplus suratensis. In this introduction of fish species, three points may be noted with specific reference to Tilapia spp.: (a) Lakes without indigenous cyprinids show marked fluctuation in fish catch with the introduction of Tilapia, and this could be stabilised by the introduction of predators and more diverse species. (b) Lakes with a moderate diversity of fish fauna show a high stabilised production with the introduction of Tilapia, presumably because of the effect of predator pressure on excessive Tilapia breeding. (c) Lowland lakes with a rich diversity of indigenous fish species colonising lakes may not require the introduction of Tilapia. Introduction of invertebrates into reservoirs in south east-Asia has not been done deliberately so far. However, the experience in other parts of the world, notably the Soviet Union, indicates that such introductions are likely to prove beneficial and to increase fish production. The potential for a considerable increase in fish production from reservoirs exists in south-east Asia. Proper management is likely to cost less than what is required for fish culture. Rural areas are likely to benefit most from increased fish production in reservoirs, and this might be a way to provide cheap protein where it is most urgently needed.

Report of the ICSF-BOBLME India (East Coast) workshop: implementing the FAO voluntary guidelines for securing sustainable small-scale fisheries in the context of food security and poverty eradication (SSF guidelines), 6-7 March 2015, Chennai, India

The workshop titled, ICSF-BOBLME India (East Coast) Workshop on Implementing the FAO Voluntary Guidelines for Securing Sustainable Small-scale fisheries in the Context of Food Security and Poverty Eradication (SSF Guidelines) was organized by ICSFin collaboration with BOBLME project.The workshop was the third in a series of consultations held in 2015 across the globe to promote the ownership of the SSF Guidelines among different stakeholders. In the run –up to the workshop, ICSF, with support from BOBLME conducted six consultation meetings with fishworkers and fishworker organizations along the east coast of India in January and February 2015. One hundred participants from India’s eastern coastal states of West Bengal, Odisha, Andhra Pradesh, Tamil Nadu and Puducherry, including women fishworkers, representatives of fishworker organizations, representatives from Department of Fisheries and other concerned departments at state and central level, Multilateral agencies, Inter-governmental organizations, Research Institutions met at Chennai, 6-7 March, 2015. The workshop was structured to facilitate active interaction and discussion among participants, taking into account linguistic diversity and the contextual differences of the marine and inland sectors. This publication—the proceedings of the Chennai workshop—will be useful for fishworker organizations, researchers, policymakers, members of civil society and anyone interested in fisheries and livelihoods.

Production of triploid African catfish, Clarias gariepinus (Burchell), using chromosome manipulation techniques

An experiment was conducted to induce triploidy in African catfish, Clarias gariepinus, using heat shock and cold shock techniques. Cold shock at a temperature of 0± 1°C and 5±1°C for a duration of 15, 30, 45 and 60 min and heat shock at a temperature of 40±0.5°C and 41 ±OS C for a duration of 1, 2 and 3 min was given to induce triploidy 5 min after fertilization. Maximum percentage of triploids (91.4%) were obtained in the heat shock at a temperature of 40±0SC for a duration of 1 min whereas cold shock at 0± 1 C for a duration of 60 min yielded 90% of triploids. Chromosome analysis revealed that diploids have 54 chromosomes and triploids have 81 chromosomes. The erythrocyte measurements of the minor axis and major axis were 1.17 times larger in treated fish than in controls. The growth studies showed that the growth rate was not significantly affected in triploids.

Cephalopod fishery at Kakinada along the east coast of India: Resource characteristics and stock assessment of Loligo duvauceli ·

At Kakinada along the east coast of India, cephalopods were exploited by trawls. Fishery occurred round the year with peak during August-October. Peak abundance and fishery of cuttlefishes coincides with this period, whereas for squids it is during March-May. Cephalopod production continued to increase initially with fishing effort, until 1995, but declined thereafter despite increased fishing effort and expansion of fishing to deeper waters. Fishery, growth, mortality, recruitment pattern and exploitation rates of Loligo duvauceli were studied. Nearly 97% of their catch was by zero year groups. They attain sexual maturity and spawn during the first year itself. Spawning occurred round the year with peak during December-February. Exploitation rate of the species is large, 0.741 compared to Emax (0.44). This indicated that their stock is under heavy fishing pressure and subjected to over-exploitation. Stock also exhibited declining trend over the years during 1995-'99. These necessitate immediate attention to avoid coHapse of the stock and fishery.

Fishery, population characteristics and stock assessment of cuttlefishes, Sepia aculeata and Sepia pharaonis at Kakinada along the east coast of India

Cuttlefishes were exploited exclusively by trawls along the coast. Growth, recruitment, mortality and exploitation rates of Sepia aculeata and Sepia pharaonis were studied. Fishery of the former was supported mainly by zero year and the latter by zero and one + age groups. Both attain sexual maturity during the first year itself and spawn during August-March with peak during November-December. Natural mortality of S.aculeata was 2.22, fishing mortality 2.34 and total mortality 4.56. It was 1.69, 1.97 and 3.66 respectively for S.pharaonis. Exploitation rate was 0.52 and Emax 0.72 for S.aculeata and it was 0.54 and 0.76 respectively for S.pharaonis. Their mortality and exploitation rates indicated that stock remains under-exploited and have considerable scope for improving the production. However, both stock and catch exhibited wide annual fluctuation with declining trend during the period. These necessitated immediate attention including measures to minimise juvenile exploitation for improving stock and fishery.