Pond culture of mud crab (Scylla serrata): an economic analysis

The findings are presented of a study conducted to determine the economic feasibility of the pond culture of mud crab (Scylla serrata) at various stocking densities. Investments, costs, and returns are given for a 1 ha crab monoculture at 4 stocking densities - 5000, 10,000, 15,000 and 20,000. Results show that mud crab monoculture in brackishwater ponds is economically feasible at stocking densities of 5000/ha and 10,000/ha.

The culture of seabass

Seabass (Lates calcarifer) are raised in ponds and cages in Southeast Asia. Details are given of the 2 phases involved in the pond and culture culture systems -- nursery and grow-out. Both monoculture and polyculture systems are used for pond production of seabass. Polyculture may involve milkfish and tilapia, groupers, seaweed, tilapia or snapper, grouper and shrimp.

AQD recommends semi-intensive milkfish culture

Details are given of a system for semi-intensive milkfish (Chanos chanos) vulture recommended by the SEAFDEC Aquaculture Department, under the following headings: 1) Pond preparation; 2) Pest (snails) control; 3) Pest (tilapia and other fish) control; 4) Fertilizer application; 5) Stocking density in nursery ponds; 6) Stocking density in grow-out ponds; and, 7) Water management.

Catfish culture in Southeast Asia

Catfish rank fifth in the world in terms of fresh and brackishwater fish culture. In Asia and the Pacific, the Clariidae family dominates production, representing nearly 80% of the total catfish production. Among the most cultured species are Clarias batrachus, C. macrocephalus, C. gariepinus. The domestic market generally absorbs catfish produce in Asia, although high-producing countries like Thailand and Vietnam engage in export. There are two basic markets for catfish: live fish and processed fish. Particular details are given of catfish production in Thailand, Indonesia and Malaysia.

Effects of cage fish culture on water quality and selected biological communities in northern Lake Victoria, Uganda

Growing of fish in cages is currently practiced in Uganda and was first introduced in northern Lake Victoria in 2010. An environment monitoring study was undertaken at Source of the Nile, a private cage fish farm, in Napoleon gulf, northern Lake Victoria. In-situ measurements of key environmental (temperature, dissolved oxygen, pH and conductivity) and biological (algae, zooplankton, macro-benthos) variables were made at three transects: Transect 1- the site with fish cages (WC); transect 2- upstream of the fish cages (USC-control) and Transect 3- downstream of the cages (DSC). Upstream and Downstream sites were located approximately 1.0 km from the fish cages. Environment parameters varied spatially and temporally but were generally within safe ranges for freshwater habitats. Higher concentrations of SRP (0.015-0.112 Mg/L) occurred at USC during February, September and at DSC in November; NO2-N (0.217- 0.042 mg/L) at USC and DSC in February and November; NH4-N (0.0054- 0.065 Mg/L) at WC and DSC in February, May and November. Algal bio-volumes were significantly higher at WC (F (2,780)=4.619; P=0.010). Zooplankton species numbers were consistently lower at WC with a significant difference compared to the control site (P=0.032). Macro-benthos abundance was consistently higher at the site with cages where mollusks and low-oxygen and pollution-tolerant chironomids were the dominant group. Higher algal biomass, concentration of low-oxygen/pollution-tolerant macro-benthos and depressed zooplankton diversity at WC suggested impacts from the fish cages on aquatic biota.

Framework for cage fish culture development in Uganda

This research work involved a review of scientific and technical literature on cage based fish culture technology, and assessment of the natural and socio-economic potential of thiS technology. The research also reviewed secondary data on aquaculture production from the pilot cage culture facilities at Jinja; the requirements of key targeted species for cage based fish production - the Nile tilapia; the feed requirements and implication for management; the physiochemical parameters for optimal performance of fish production in cages; and preliminary production and operational costs of cage fish production.

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.