Isolation and Identification of Bacteria found in the milt of cultured Clarias gariepinus

Bacteria identification in fish is important; hence it provides update information on emerging and existing organisms thereby enriching the gene bank on fish disease. This study investigated bacteria associated with milt in cultured samples of African catfish- Clarias gariepinus. Catfish broodstock were collected from private Fish Farm in Ogun State, Nigeria. Fish samples were taken to the Microbiology laboratory, Federal University of Agriculture, Abeokuta Ogun State for milt microbial analyses, and amplicon were taken to International Institute of Tropical Agriculture, Ibadan for molecular characterization. Bio-edit was use for importing and mining nucleotide sequences into gene bank. The results revealed that the following bacterial organisms were present in the milt of Clarias gariepinus: Aeromonas caviae, Proteus mirabilis, Serratia rubidaea, Pseudomonas mosselii, Acinetobacter soli and Klebsiella variicola. The Basic Local Alignment Search Tools revealed the percentage similarity ranging from 86- 97.04% and their accession numbers. These bacteria indicated high levels of faecal contamination in the environment. In conclusion, bacteria were found in the milt of cultured catfish and are capable of being pathogenic to humans and may increase the vertical transfer to fry during breeding and rearing stage.

Assessment of the Pollution Status of Eleyele Lake, Ibadan, Oyo State, Nigeria

Background. Lakes are a vital water resource, but are adversely affected by pollutants such as heavy metals and polychlorinated biphenyls (PCBs) from urban, agricultural and industrial activities. This can give rise to potential pollution-related health problems such as cancer and infectious diseases. Risk assessments are necessary to determine the degree of pollution and its effects on human health and ecological systems. Objectives. This study assessed the pollution status and a risk assessment was calculated to determine the degree of the pollution and its effects on the human health and the ecological system of Eleyele Lake in Ibadan, Nigeria. Methods. Physical and chemical parameters, heavy metals and PCBs were determined in the lake water using standard methods from December 2013 to February 2014 at ten different sites of anthropogenic activity. Results. Water pH ranged from 6.00–7.50, while electrical conductivity ranged from 205.00–221.00 μs/cm3. Dissolved oxygen ranged from 0.30–6.00 mg/L and total dissolved solids ranged from 105.00–113.00 mg/L. Phosphate levels ranged from 13–0.99 mg/L. Nitrate and sulphate in the dry season ranged from (3.10–3.80 and 35.81–40.97 mg/L) and (0.12– 0.37 and 6.10–10.30 mg/L) in the wet season. Heavy metal concentrations were in the order cadmium (Cd) > zinc (Zn) > copper (Cu) > chromium (Cr) > lead (Pb) for the dry season and Cd > Zn > Cr > Pb > Cu for the wet season. Total PCBs ranged from 493.90–732.55 μg/L and 52.00–390.03 μg/L for the dry and wet seasons, respectively. All determined physical and chemical parameters were within permissible levels, while heavy metals and PCB concentrations were higher than permissible levels. Discussion. The hazard quotients and carcinogenic risk values were greater than acceptable limits, indicating that PCBs in Eleyele lake water pose adverse health effects to the local population. It was observed in this study that lower chlorinated PCBs were more prevalent than higher chlorinated PCBs. This may be attributed to the fact that the lower chlorinated PCBs are influenced by atmospheric deposition as a result of their volatility, and they are more susceptible to atmospheric transport than highly chlorinated PCBs. Conclusions. PCBs possess serious health risks to the population that depends on the lake as a source of domestic water and its aquatic organisms. Efforts are needed to reduce anthropogenic influence on the lake through strict environmental controls. Competing Interests. The authors declare no financial competing interests

Extraction and Utilization of Chitin and Chitosan from Waste Yields of Economically Important Crustaceans and Molluscs for Improved Fish Production

Background: Every year, about eight million tons of different species of crustacean shells are produced, with several million tons of various mollusc shells world-wide. These shell wastes are usually disposed into the water body or mainland, littered everywhere, with significant impact on the environment. Aim: To provide a profitable way of reducing and possibly removing shell wastes, and harness them for a better purpose through an eco-friendly and sustainable technological approach. Main Body of the Abstract: This review underscores a broad list of economically important crustaceans and molluscs, harvestable in Nigeria coastal waters whose shells usually ended up as wastes. Chitin, being the primary component of these wastes can be extracted and deacetylated into chitosan, or synthesized into nanoparticles for better applications in various aspects of aquaculture. Both chemical and biological methods of chitin extraction were discussed, however, bioextraction method was recommended due to its eco-friendliness, biocompatibility, and non-hazardousness. Various ways by which these shell wastes can be processed and utilized for improve aquaculture practices were also discussed. These include fish growth enhancement, pond water treatment, as antioxidant, as immuno-stimulant, as antimicrobial, as drug carrier, and several other purposes. Conclusion: There are much hidden wealth in these fisheries by-products (Crustacean and Mollusc shells) if properly valorized. It has a great potential to transform aquaculture industry, and bring significant, and sustainable economic development in Nigeria

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