Summer yield of fish in polyculture in Transkei, South Africa, using pig manure with and without formulated feed

No Abstract

THE USE OF HOLDING CAGES FOR THE SPAWNING OF CLARIAS-GARIEPINUS

Use is made of plastic covered wire mesh cages to minimise the stress and physical damage caused by the inherent aggression of Clarias gariepinus during the spawning phase. The cages enable a single person to perform the entire hormonal injecting programme with a minimum of stress in a relatively short period of time

THE INFLUENCE OF DIFFERENT DIETARY LIPIDS ON THE GROWTH AND BODY-COMPOSITION OF THE AFRICAN SHARPTOOTH CATFISH, CLARIAS-GARIEPINUS (BURCHELL)

The influence of various lipid sources on the muscle fatty acid composition of juvenile African sharptooth catfish Clarias gariepinus, was tested Juveniles were fed an artificial diet,for 60 days, containing no lipid (Al control), or the following lipids at 10% of the diet, sunflower oil (B, a high level of C18:1 omega 9 and C18:2 omega 6), cod liver oil (C, a high level of 20 and 22 C omega 3 fatty acids) and tallow (D, predominantly SFA and MUFA). The best growth was achieved by fish fed the sunflower diet. Muscle total lipid composition was strongly influenced by diet and contained the following SFA, MUFA and PUFA percentages, and a omega 3/omega 6 ratio of A, 36.33; 45.13; 15.70% & 0.52; B, 30.78; 34.54; 33.96% & 0.11; C, 33.51; 38.75; 24.59% & 1.87; D, 38.87; 46.03; 13.06% & 0.44, respectively

COMPARISON OF HUMIDITY CHAMBER, MARISOURCE HATCHING-TRAY AND ZUGER GLASS FUNNEL INCUBATION SYSTEMS FOR BREEDING OF CYPRINUS-CARPIO (L) AND CLARIAS-GARIEPINUS (BURCHELL)

Humidity chamber, MariSource hatching-tray and ''Zuger'' glass funnel incubation systems were compared for hatching successes of both Cyprinus carpio and Clarias gariepinus fertilised eggs. The humidity chamber incubation system proved superior for C. carpio, whilst the MariSource hatching-tray system was better for C gariepinus. Fungal infections greatly influenced hatching results

Thermal effect on the life-cycle parameters of the medically important freshwater snail species lymnaea (radix) luteola (lamarck)

The snails Lymnaea (Radix) luteola exhibited marked variations in growth, longevity, and attaining sexual maturity at different temperatures and diets. At 10 C, irrespective of foods, pH and salinity of water, the snails had minimum life span, maximum death rate and lowest growth rate. At 15 C, the growth rate was comparatively higher and the snails survived for a few more days. But at these temperatures they failed to attain sexual maturity. Snails exposed to pH 5 and 9 at 20 , 25 , 30 , 35 C and room temperatures (19.6 -29.6 C); to 0.5, 1.5 and 2.5 NaCl at 20 and 35 C; to 2.5 NaCl at 25 C and room temperatures failed to attain sexual maturity. The snails exposed to pH 7 and different salinity grades at 20 , 25 , 30 , 35 C and room temperatures became sexually mature between 25-93 days depending upon the type of foods used in the culture