Bacterial flora of the gut of the African snakehead, Channa obscura (Pisces: Channidae)

A qualitative and quantitative investigation of the bacterial flora of the gut of the African snakehead, Channa obscura was undertaken. The types of bacteria isolated from the different parts of the gut of C. obscura include Pseudomonas, Streptococcus, Citrobacter and Proteus. The coliform (Escherichia coli, Enterobacter) and some other Enterobacteriaceae such as Salmonella were also present. The stomach and intestine were found to have a preponderance of Pseudomonas and Vibrio species. Klebsiella sp. and Bacillus sp. (only in the pyloric caeca) were also isolated. On the whole, the correlation coefficients of the two incubation temperatures showed a high statistical significance. Thus the bacterial load of the gut of C. obscura has been shown as a function of temperatur

Digestive enzymes in the alimentary canal of Clarias anguillaris (Pisces: Clariidae)

Three groups of digestive enzymes were observed in the alimentary canals of the fingerlings and adults of Clarias anguillaris. The enzymes were carbohydrases including amylase, sucrase, lactase and maltase, proteases including peptase, tryptase and peptidase, and lipase. The activities of the protease were found to be higher in the fingerlings than in the adults while carbohydrases' activities were higher in the adults than fingerlings. Amylase was most widely distributed, found in both fingerlings and adults and in every region studied; it was followed by lactase. Of the proteases, peptase was found to have the widest distribution. Lipase activity was found in the alimentary canal of the adults. Tropical Freshwater Biology VOL. 8 1999, pp. 55-63 KEY WORDS: digestive enzymes – carbohydrases – proteases – lipases - Clarias anguillari

Acute toxicity of potassium permanganate to fingerlings of the African catfish, Clarias gariepinus (Burchell, 1822)

Laboratory static bioassays were conducted to determine the 96-h LC50 and the lethal levels of concentrations of the aquaculture therapeutant, potassium permanganate (KMnO4) on fingerlings (meanweight, 6.24 ± 0.15 g and mean length, 4.25 ± 0.07 cm) of the African catfish, Clarias gariepinus. A total number of one hundred and eighty (180) fingerlings of mixed sex and brood stock were used for thetoxicity bioassay. The 96-h median lethal concentration (LC50) value obtained for treatment of the fingerlings of the catfish C. gariepinus with potassium permanganate was 3.02 mg/L KMnO4 with lowerand upper 95% confidence limits of 0.40 and 3.73 mg/L KMnO4, respectively. There was very strong and positive correlation between the variables (r = 0.96) with 93% (r2) association. Toxicity curve revealed 11.20 mg/L KMnO4 at 8.20 h as the threshold value for the 96 h assay of potassium permanganate on fingerlings of C. gariepinus. The 96 h LT50 for 10, 8 and 6 mg/L KMnO4 to the test fish were alsodetermined to be 10.40, 11.30 and 17.80 h, respectively. Varying behavioural patterns were observed in the fish, which included erratic swimming, loss of reflexes, total loss of equilibrium, paleness of skinand gasping for air. The value of water quality parameters monitored during the exposure period did not differ significantly (P>0.05) within the various concentrations of the therapeutant (KMnO4) as well aswith the control. However, pH and total alkalinity tended to increase with increasing concentration of the toxicant

Acute toxicity of refined oil on the catfish, Clarias gariepinus (Teugels, 1984) (Pisces: Clariidae)

Laboratory static bioassays were conducted to determine the 24-, 48-, and 96 -hour LC50 and the lethal levels of concentrations of oil-in-water dispersions (OWD) of used and fresh fuel oil for embryo, fry and fingerlings of the catfish Clarias gariepinus(Teugels, 1984). The most sensitive was the embryonic stage while the fingerlings were most resilient. The LC50 values obtained for treatment with fresh fuel oil were as follows: Embryos (24- and 48 -hour LC50) 0.034 ml/l and 0.042 ml/l respectively. For the fry (24-, 48-, 72- and 96-hour) the LC50 values were 1.22ml/l, 0.85ml/l, 0.83ml/l and 0.70ml/l respectively. The fingerlings had 48-, 72 and 96-hour LC50 values of 5.00 ml/l, 2.30 ml/l and l.78ml/l respectively. The LC50 values for treatment with used fuel oil were as follows: Embryos (24 - and 48 -hour LC50) 0.032 ml/l and 0.04 ml/l respectively. For the fry (24-, 48-, 72-and 96-hour LC50) values were 1.59 ml/l, 1.14 ml/l, and 1.12 ml/1 while the fingerlings had 0.82 ml/l, 1 .37 ml/l and 1.02 ml/l as their 48-, 72- and 96-hour LC50 values respectively. Loss of skin pigmentation was observed in fish exposed to fresh fuel oil and darker pigmentation in fish exposed to used oil. Activity generally decreased with increased concentration of toxicant and longer duration of exposure. A similar trend was observed for hatchability of the embryos. Increased mouth and opercular breathing were also observed. Tropical Freshwater Biology VOL. 8 1999, pp. 17-26 KEY WORDS: Petroleum-Refined Oil-Toxicity-Behaviour-Clarias gariepinus, Nigeria

Haematological characteristics of the African snakehead, Parachanna obscura

The haematological characteristics of the African snakehead Parachanna obscura includes mean blood haemoglobin concentration of 5.70g/dl, mean haematocrit of 19.20%, mean red blood cell count of 1.67 x 10 12/L, mean total white blood cell count of 19.07 x 103 mm-3, mean erythrocytic haemoglobin concentration of 29.08%, mean erythrocytic haemoglobin of 39.86 g, mean erythrocytic volume of 132.84 μ3, mean total plasma protein of 4.45 g/dl and mean plasma glucose of 67.42 mg/dl. Correlations were found with certain blood parameters as function of the length, weight and condition factor..African Journal of Biotechnology Vol. 4 (6), pp. 527-530, 200