The normal intestinal anaerobic bacterial flora of fish for the most part remains unknown. The role of anaerobic bacteria in disease, digestion, nutrition, and the immune response has never been thoroughly investigated. The purpose of this on-going research is to isolate and identify the anaerobic intestinal flora of two representative fish species, namely, Rainbow trout (Oncorhynchus mykiss), and the freshwater Angelfish (Pterophyllum scalare).

Samples for bacterial culture are grown in a Bactron II anaerobe chamber on pre-reduced anaerobically sterilized (PRAS) media. Isolated anaerobes are identified by aero tolerance and biochemical reactions. Antibiotic sensitivity patterns are determined.

To date, several anaerobic genera have been identified from angelfish, while only one, Clostridium, has been identified from trout. Several species of Clostridium appear to be present in the gut of trout. This preliminary data indicates that the diversity of flora may vary with host species.