Aflatoxins associated with storage fungi in fish feed

Abstract

Cereals and legumes are a very important part of feed used in culturing fishes. Feed, when not properly stored, enhances the growth of storage fungi which is a  source of mycotoxins, secondary metabolites produced by storage fungi. This study investigates storage fungi and aflatoxin in fish feed stored under three different  storage conditions. Storage fungi were isolated and identified using direct isolation technique; detection and identification of aflatoxins using the High Performance Liquid Chromatography and Proximate analysis of the stored feed were also carried out. Two fungi species (Mucor species and Fusarium oxysporium) were isolated from the stored feed. It was observed that it takes five weeks after sporulation of storage fungi for production of mycotoxins to take place. Four types of Aflatoxins  (G1, G2, B1 & B2) were identified in the stored feed. The results on the proximate analysis on the stored feed prior to and after storage periods revealed decrease in  the carbohydrate, protein, ash and the crude fiber content of the stored feed and increase in the moisture and crude fat content of the feed. The results from this  study revealed that good storage condition is very essential and there is need for further work to assess the implication of aflatoxin on the health of fish and human (final consumer).

Keywords: Storage fungi, aflatoxins, fish feed, proximate analysis