ISOLATION OF FUNGI FROM FISH FEED SAMPLES IN BENIN CITY

ABSTRACT

Fish and fish products are a popular source of protein and animal fat to the people, and the demand for protein is increasing. The global demand for formulated feeds for fish was estimated to be 29.3 million tonnes in 2008 and is expected to grow with increasing aquaculture. This study was aimed at isolating fungi from fish feeds sold in Benin City. Four (4) brands of fish feeds were obtained from five (5) different stores. Serial dilutions were made using sterile distilled water as diluent. Enumeration and isolation of fungi and aflatoxigenic fungi was carried out using potato dextrose agar and Aspergillus flavus and parasiticus agar AFPA. The pour plate method was employed, plates were incubated at 28 ± 2°C for 7 days. Cultural and morphological characterization were performed for the identification of fungal isolates. The temperature and relative humidity values of the feed stores were determined using a thermometer humidity meter (ThermoPro, TP49-W-2). The total fungal count of fish feeds sampled, ranged from 0.01 ± 0.00 x 10⁶ to 1.82 ± 38.00 x 10⁶ cfu/g. The aflatoxigenic fungal count ranged from 1.00 ± 0.00 x 10⁴ to 3.00 ± 0.00 x 10⁴ cfu/g. However, only growth of Aspergillus flavus was observed. The fungal species isolated from the fish feed samples include; Aspergillus niger, Mucor spp. Penicillium spp. Fusarium spp. andSaccharomyces cerevisiae. The percentage frequency of occurrence of fungal isolates ranged from 11.76% (Penicillium spp. Aspergillus niger and saccharomyces cerevisiae) - 47.07% (Fusarium spp.) The temperature readings of the fish feed stores ranged from 33.90°C (store A) - 35.00°C (store E). The relative humidity readings of the fish feed stores ranged from 66% (store B) - 76% (store D). There is therefore need for frequent detection of aflatoxigenic fungi in fish feeds and sensitization on ways of minimizing fungal contamination and proper storage of fish feeds.