Showing papers on "Polyculture published in 1992"

Ecological aspects of fish species interactions in polyculture ponds

Abstract: The relationships between cultivated fish species and their environment is largely dependent on the biological characteristics of the fish and the degree of intensification of the culture. In extensive and semi-intensive systems, based on natural production, stocking fish species of different feeding habits together enables a more efficient utilization of pond resources. In polyculture systems only a proper combination of ecologically different species at adequate densities will utilize the available resources efficiently, maximize the synergistic fish-fish and fish-environment relationships and minimize the antagonistic ones. Synergistic interactions among fish species may be explained on the basis of two interrelated processes: increase of food resources and improvement of environmental conditions. Antagonistic interactions occur between incompatible species combinations and when the stocking rates are balanced; in this case, the way the system is affected depends on the food chain level were the imbalance occurs. Several examples of synergism and antagonism at different levels of the food chain are analyzed in this paper. The knowledge of fish-fish and fish-environment quantitative relationships enables choosing adequate combinations of fish species, stocking rates, input types and rates, and other management decisions according to the specific local conditions: climate, quality of water supply and pond fertility, availability of fish fry and fingerlings, availability of feeds and fertilizers, and market requirements.

Polyculture of Channel Catfish and Blue Tilapia in Cages

Abstract: Blue tilapia (Tilapia aurea) were raised at four densities (0, 25, 50, and 75 fish/m3) in 1-m3 cages with 400 channel catfish (Ictalurus punctatus) for 140 d. Each treatment was replicated in three ponds. Growth of channel catfish increased significantly with increasing numbers of blue tilapia (P ≤ 0.01). Linear regressions described the relationship between channel catfish growth in length (r 2 = 0.83) or weight (r 2 = 0.88) and numbers of blue tilapia.

A cost benefit analysis of fish culture strategy towards the control of mansonioides in Shertallai, Kerala state.

Abstract: The cost benefit analysis of fish culture as a means for vector control towards the containment of Brugian filariasis in Shertallai, a highly endemic tract for this disease in Kerala was carried out. While the financial gain accrued to the community was to the tune of Rs. 1,82,052 in ponds (under monoculture) with Chinese grass carp from 763 ponds, it was Rs. 1,83,740 from 1000 ponds under polyculture with Catla catla, Cyprinus carpio, Labeo rohita, Labeo fimbriatus, Cirrhina mrigala and Ctenopharyngodon idella (Chinese grass carp). Monoculture with Giant gourami (Osphronemous goramy) fetched an income of Rs. 7,654 to the community from 128 ponds. A marked reduction in weed reinfestation/vector breeding was observed in ponds under fish culture than other without fishes. The study clearly indicates that fish culture is an ideal strategy for Mansonioides control as it can bring perceptible benefits to the community.

Evaluation of the poly- and monoculture production of the common carp Cyprinus carpio L. and the sharptooth catfish Clarias gariepinus (Burchell) in final effluent oxidation pond water of a sewage purification system

Abstract: The two fish species Clarias gariepinus and Cyprinus carpio were produced in poly- and monoculture in final effluent sewage maturation pond water. Yields of more than 6 t of fish.ha-1 were obtained in polyculture within a 100 d production period using overwintered juvenile stock. Late summer production under monoculture conditions for each species was, however, less favourable partly due to the water temperatures which dropped to below 20°C and the use of juvenile fish bred during the same season