Erick Ochieng Ogello

COMPARATIVE GROWTH PERFORMANCE OF MALE MONOSEX AND MIXED SEX NILE TILAPIA (Oreochromis niloticus L.) REARED IN EARTHEN PONDS

Comparative growth performance of male monosex and mixed sex Nile tilapia (Oreochromis niloticus ) was conducted in six earthen ponds each measuring 150 m 2 at the Kenya Marine & Fisheries Research Institute (KMFRI), Kegati Aquaculture Research Station. Male monosex and mixed sex of O. niloticus juveniles at an average weight of 12.2 ± 0.02 g and average length of 7.6 ± 0.02 cm were collected from nursery production ponds. The male monosex juveniles were obtained by feeding newly hatched juveniles with feed dosed with 17 α methyl testosterone hormone for a period of one month. Stocking was at 3 juvenile

Substitution of fish meal with sunflower seed meal in diets for Nile tilapia (Oreochromis niloticus L.) reared in earthen ponds

ABSTRACT This study investigated sunflower seed meal (SSM) as dietary protein replacement of fish meal (FM) for Nile tilapia (Oreochromis niloticus) juveniles (initial mean weight of 19.8 ± 6.3 g) reared in earthen ponds for 210 days. SSM replaced 25%, 50%, 75%, and 100% (i.e., D25, D50, D75, and D100, respectively) of FM in an isonitrogenous and isocaloric diet. The optimum FM replacement level of D25 as predicted by the equation y = 177.5 + 26.5x – 7.9x2 yielded an optimum weight of about 184 g within 100 days. Thus D25 was the most effective SSM level for Nile tilapia growth in earthen ponds. Fish growth declined as SSM exceeded D25. The length-weight relationship (r ≥ 90%) depicted an isometric fish growth. Nutrient utilization parameters were similar in all the diets except for D100. The protein content of fish carcass was highest in the control and D25, while fiber level was highest in D100. Amino acids imbalance and high fiber content could have reduced the fish growth at D50, D75, and D100.

Haematological Response of African Catfish (Clarias gariepinus Burchell 1822) Fingerlings Exposed to Different Concentrations of Tobacco (Nicotiana tobaccum) Leaf Dust

The present study set out to investigate the haematological effects of tobacco leaf dust on African catfish, Clarias gariepinus, fingerlings, with a mean weight of 3.01 ± 1.25 g using “static renewal bioassay system” during a 120-hour bioassay exposure period. Water quality parameters such as pH and dissolved oxygen significantly decreased while total alkalinity and conductivity increased significantly in the exposed media, compared to the control test. Leucocytes counts increased significantly while erythrocytes counts decreased significantly with increasing concentration of tobacco dust. Packed cell volume significantly reduced with increase in the concentration of tobacco dust. Haematological examination showed that there was destruction of the erythrocytes production, and the concentration of haemoglobin was much lower in the exposed fish compared to the control depicting an anaemic condition. The results could provide baseline information for the safe limits of using tobacco leaf dust in fish ponds; hence 1.56 g L−1 concentration of tobacco leaf dust was recommended for pond preparation for Clarias gariepinus fingerling stocking. For better survival rates, the fish should only be introduced in the pond after three days of tobacco application.