Food and Feeding Habits and Allometric Relationship of Synodontis schall in Lower Ogun River, Akomoje, Ogun State, Nigeria

Overfishing and depletion of wild fish stock are a major problem facing the fisheries sector in Nigeria, hence the need to carry out an extensive research on the biology of wild species. The aim of this study was to provide contributory information on the biology of Synodontis schall from Ogun River, Nigeria. Ninety fish samples were obtained from local fishermen bi-monthly between February and August, 2015. The length and weight of the specimen were measured and length-weight relationship was determined using the formula W=aLb. Gut content of the specimens was studied using the frequency of occurrence and numerical method. Index of stomach fullness was also determined monthly. Gut content revealed both plants and animal items consisting mainly of insects, rotifers, crustaceans, fish parts, algae etc. indicating omnivorous feeding habit. Percentage stomach fullness was higher during the peak of the wet season (July and August). Total length, standard length and weight of specimens were ranged between 15.4 and 29.0 cm, 10.1 and 23.5 cm and 50 g and 198 g, respectively. Length-weight analyses gave the values of ‘b’, ‘a’, and ‘r’ as 1.520, 1.115 and 0.8967, respectively, exhibiting a negative allometric growth pattern. The study therefore, shed light on the biology of the species and thus, contributes to documented facts about the species from the Akomoje reservoir, with a view towards developing the aquaculture of the reservoir

PATHOLOGICAL STUDY OF CLARIAS GARIEPINUS (BURCHELL, 1822) SUB-ADULT ARTIFICIALLY INFECTED WITH PSEUDOMONAS AERUGINOSA

Hematology and histopathological variations in Clarias gariepinus sub-adults subjected to oral challenge with Pseudomonas aeruginosa ATCC27853 were studied for a period of 21 days, with a view to assess the pathogenesis of the bacteria and compared with a control. The results were compared statistically using One-way ANOVA. The symptoms of the infected fish included tail and fin rot, internal hemorrhages and skin patches of superficial ulcers. Tissue sections revealed marked loss and sloughing off of the gill lamellar epithelium, liver showed that hepatocytes appear finely reticulated and foamy; however there were a few foci of large cytoplasmic vacuolations of the hepatocytes and the sinusoids were moderately congested while the intestine showed shortened rugae; the submucosa glands were reduced in numbers; however the surface epithelial cells appeared to be proliferating rapidly and immature (hyperplastic). There was a significant reduction in the mean values of packed cell volume from 34.67±5.2% to 22.33±0.3%, hemoglobin from 9.77±0.2g/dL to 6.97±0.2g/dL, red blood cell from 2.23±0.3x1012/L to 1.27±0.1 x1012/L and lymphocyte count from 69.00±2.3% to 52.33±0.9% of C. gariepinus after three weeks of exposure to P. aeruginosa. However, the reverse was the case in the mean values obtained for white blood cell and neutrophil for infected fish which were reasonably higher when compared to that of uninfected fish (17.13±0.5 to10.80±0.3x109/L) and (47.33±1.2% to 30.33±2.9%) respectively. It could therefore be concluded that changes in organs and blood parameters of fish occur proportionately to pathogen invasion