Haematological profile of Heterobranchus bidorsalis (Geoffroy St. Hilaire 1809) was determined. Haematocrit values, haemoglobin concentrations, erythrocyte and leucocyte counts, mean cell haemoglobin concentration, sodium and potassium ions concentrations were 24.75±1.23%, 5.43±0.25 g/100 ml, 1.99±0.52 10"/mm 3 and 7.25±0.60 10 4 /mm 3 , 22.11±0.77%, 802.52±36.97 and 83.54±5.05 mgfl, respectively.H. bidorsalis fingerlings were subjected to a range of salinities, 0, 3, 6, 9, 12 and 15 ppt. The optimum salinity range for survival and good growth performance was determined as 0-3 ppt. Survival was > 85% from 0-9 ppt with no significant differences (P> 0.05), but decreased progressively as salinity increased.Qualitative and quantitative assays of digestive enzymes in the different regions of H. bidorsalis guts revealed an array of carbohydrases, proteases and lipases. Enzyme activity was restricted to the stomach, duodenum and ileum with fewer enzymes recorded in the stomach. The pattern of distribution and relative activity of enzymes correlated with its euryphagous diet.Parasitological examinations conducted on the skin and internal organs of H. bidorsalis yielded a variety of parasites which included three protozoans, two monogeans, six digeneans, four cestodes, two nematodes, two annelids and four copepods. No acanthocephalan infection was detected. Protocephalus sp. (Cestoda) and Allocreadium sp. (Trematoda) had the highest prevalence (>81%) followed by digenean metacercaria (35%).The implications of these results in relation to the aquaculture potential of this catfish is discussed.

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Dry diets containing either fish meal (C-FM) or dried fermented fish silage and soybean meal blend (l:l,ww-') (C-FS) as the sole protein source, were fed to triplicate groups of juvenile Clarias gariepinus (10.8 5 0.3 g) at 5% body weight per day for 70 days.Catfish fed the C-FS diet showed reduced (P < 0.05) growth rate, feed conversion, protein eficiency and digestibility. Lower amounts of available amino acids in the C-FS diet resulted in inferior nutritive value for catfish growth than in the C-FM diet. Postprandial changes in plasma amino acids showed similar patterns in both diet treatments, but the maximal mean levels attained for the C-FS diet were correspondingly lower and occurred earlier than with the C-FM diet. There wcre no effects of feeding C-FS diet on the hepatosomatic index but carcass analysis showed that body protein deposition was lower (P < 0.05). Differences in haematocrit, haemoglobin content and liver histology were demonstrated but were not pathological. Lower digestible energy of C-FS diet also contributed to the poor performance of catfish in this treatment. Results of this study indicate that C. gariepinus cannot metabolize protein from co-dried fish silage as efficiently as fish meal protein when used as the sole dietary protein.