Length-weight relationship (LWR), condition factor (K) and stomach content of three cichlid fishes (Hemichromis bimaculatus, Sarotherodon melanotheron, and Chromidotilapia guentheri) were calculated at Eleiyele reservoir, Nigeria, Africa. The fish were collected monthly from fishermen during the dry season (January-March 2001) and the rainy season (April, May, June 2001). Gill nets of mesh sizes 50-55 mm were used. The LWR had a significant correlation for the three species and the growth exponent (b) for H. bimaculatus indicates a negative allometric growth (S. melanotheron and C. guentheri had isometric growth). Condition factor values were higher than one in the three species, and varied with size and season. Stomach contents revealed that the three species are omnivorous and that diet composition varies seasonally.

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Fluctuating asymmetry (FA), often used as indicator of environmental stress, was evaluated in gill rakers and filaments of Labeo ogunensis from Ogun river, Southwest Nigeria. Mean length and weight of 13.68+1.28 cm and 59.40+17.48 g were respectively recorded. The gill rakers (t = -0.919) and filaments (t = -1.150) from both sides were not significantly different. The gill filaments recorded (0.31+2.42) higher incidence of fluctuating asymmetry (FA) compared with the gill rakers (0.21+1.58), signifying developmental interference in the population. Fish size and sex were observed to exert minimal influence on FA.

Diet and dietary habits of African Butter Catfish Schilbe mystus (Linne, 1766), an economically important fish in Oyan and Asejire lakes (Southwest Nigeria) were examined between July 2000 and December 2001. Stomach contents were analysed using the numerical, frequency of occurrence and points methods. The fish is predatory but the diet differs among lakes and seasons. Insects were more important in the diet of small (

We investigated the presence and levels of 11 polynuclear aromatic hydrocarbons (PAHs) in 4 commonly consumed roasted food delicacies in Owerri, a southeastern city of Nigeria. Freshly roasted plantain, yam, fish and meat (popularly called suya) samples were purchased from 10 roadside fast-food sellers in the municipality, preserved in labelled sterile amber bottles with benzene and taken to the laboratory in iced-chest. A gas chromatograph coupled with flame ionization detector (GC-FID) was used in the analysis of samples. The single factor ANOVA and means plots were used to detect homogeneity in mean variance and structure of group means of the PAHs determined in the foods, respectively. Roasted plantain contained the highest level of combined PAHs measured (0.0465 mg/kg), followed by suya (0.0372 mg/kg); with mean concentrations of 0.004227 (± 0.0019135) and 0.003382 (± 0.0023045) mg/kg, respectively. However, least concentration of the combined PAHs of 0.0135 (0.001227 ± 0.0004152) mg/kg was recorded in roasted fish. There was significant heterogeneity [F (214.52) >F crit(3.95) ] at P<0.05 (95% confidence limit) in the concentrations of the PAHs in the foods sampled. Post-hoc means plots revealed that the heterogeneity was most contributed by fluorene in suya, acenaphthene and phenanthrene in roasted fish, phenanthrene and anthracene in roasted plantain, and anthracene in roasted yam samples. The higher concentrations of these hydrocarbons in suya than roasted yam could be due to the longer roasting duration, higher fat content of meat, and pyrolysis resulting from melted fat from meat dropping onto the heat source. However, the higher concentrations of combined PAHs recorded in roasted plantain than meat (suya) and roasted fish could be due to the closer distances the plantain samples were (usually) placed to the source of the heat and the higher temperature required for roasting the plantains than meat and fish. The study reveals high concentrations of the PAHs in the foods sampled. This therefore places the several consumers at potential health risk.