Effect of brood stock size on egg fertilization, hatchability and fry survival rate of African catfish (Clarias gariepinus)

This experiment was conducted to investigate the effect of size of brood stock on egg fertilization, hatchability and fry survival rate of Clarias gariepinus in an intensive culture system, for a period of four weeks. Larger brood stock size (1200-1500g) produced larger eggs and bigger fry while moderate brood stock size (795-1000)g produced moderate eggs and moderate fry. The mean size of eggs produced and the size of brood stock was however not significantly different (p > 0.05). In addition, larger eggs resulted in larger fry. The survival rate of fry after starvation increased with increase in parent brood stock size. Best on this study it was recommended that for larger eggs and fry production, brood stock of Clarias gariepinus, of average size of (1200-1500g) should be selected for use in fish hatchery operation in Nigeria. There was no significant difference (p> 0.05) in the physiochemical parameters.Keywords: Broodstock, Egg fertilization, Hatchability, Clarias gariepinu

Occurrence of pathogenic bacteria associated with Clarias gariepinus in selected fish farms of Kumbotso local governement area of Kano state, Nigeria

With the diminishing rate of natural fish resources globally, a reasonable percentage of fish and fish products supply now comes from aquaculture. However, quality production is highly required for sustainable demand and supply. It is in view of the aforementioned that this study was designed to examine the quality status of Clarias gariepinus in relation to pathogenic bacteria in two fish farms in Kumbotso Local Government Area of Kano State, Nigeria. 66 Clarias gariepinus with bodyweight 17g - 215g were randomly sampled from July to December 2012 followed by the isolation and identification of different pathogenic bacteria from skin and gill. A total of 132 samples comprising skin (1cm2) and gill (1g) were subjected to microbiological assays in the laboratory following standard procedures. Nutrient Agar, MacConkey Agar, Eoisin Methylene blue, Salmonella Shigella Agar and Blood Agar were used for isolation and maintenance of cultures during the study. Lactose broth, Brilliant Green lactose bile broth (BGLB) was used for the estimation of Escherichia coli Most Probable Number per 1cm2 of skin and 1 gram of gill (MPN/ml and MPN/g). The highest mean of Aerobic Plate Count (APC) was 1.26 x 104 cfu/ml while the highest mean of Escherichia coli MPN/1cm2 was 8.75. Bacterial pathogens isolated and percentage occurrences in parenthesis were Escherichia coli (54.27 %); Stapholococcus aureus (22.48 %); Pseudomonas aeruginosa (10.85 %); Salmonella paratyphi (9.30 %) and Enterobacter aerogenes (3.10 %). There was no significant difference (χ2 = 3.42, P > 0.05) in bacteria isolates from the two fish farms. The result from this study indicated that the fishes were less contaminated with pathogenic bacteria, thus consumers are safe to eat fishes harvested from these farms since all the values are within the recommended limit of < 5 x 105 cfu/g for APC and, 11 for Escherichia coli MPN/ml by International Commission for Microbiological Specification for Food (ICMSF, 2007).Keywords: Fish farm, Clarias gariepinus, Microbiological assays, Pathogenic bacteria

Tree Species Diversity in Kakulu Forest of Zing L.G.A., Taraba State, Nigeria

No abstract