Gregory Ejikeme ODO, Helen Ogochukwu NWAMBA, Joseph Effiong EYO


Studies on some aspects of the biology of Heterotis niloticus in Anambra river were carried out for 22 months. Analysis of the stomach content of 546 species of H. niloticus in Anambra river established the preponderance of plantivorous crustacean, copepods and cladocera throughout the four maturation stages examined. Seasonal variations occurred in the dietary components of the fish. The length-weights relationship and the relative condition revealed that females had better condition. The mean length and weight were 94.5 ± 60 cm (29 – 167 cm) and 120 ± 21.8g (10 – 250g) respectively. A sex ratio of 1:0.8 (M: F) at Otuocha was more pronounced than at Ogurugu and Nsugbe. Digestive enzyme assays in the different gut regions (oesaphagus, stomach, pyloriccaeca, ileum and rectum) of H. niloticus showed an array of glycosidase (amylase, sucrase, malatase, lactase, cellulase); protease, (pepsin, trypsin, chymotrypsin) and lipases. The pattern of spread and relative activity of the enzymes is consistent with its planktophagous diet. Haematocrit values, haemoglobin concentrations, erythrocyte and leucocytes counts, mean cells haemoglobin concentrations, plasma protein, glucose, albumin and inorganic ion (sodium, chloride, calcium, potassium, magnesium, phosphorus) for H. niloticus were established. Correlations were found between some blood parameters and standard length. 

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