Combined with previous studies –, our results indicate that bacteria and fungi co-inhabit the GI tract of P. nigrolineatus, with the potential of degrading dietary wood. Ongoing studies [30, McDonald, Watts and Schreier, manuscript in preparation] suggest that the enteric bacterial community may lack selected enzymatic activities essential for lignocellulolytic digestion, which may be provided by the fungal community and/or host. ITS1/ITS2 sequences for several cellulase-producing fungi have been found in the present study, including those having similarity with F. oxysporum, A. pullulans, Botrytis caroliniana, Metschnikowia, Alternaria and Debaryomyces. F. oxysporum, which dominated foregut and midgut regions, excretes enodocellulases, exocellulases and β-glucosidase . These cellulolytic activities might allow the bacteria to benefit from the primary stage of cellulose degradation as part of a synergistic relationship. While there are different fungi in different regions of each fish, many may be carrying out equivalent roles, acting on cellulose to enhance and augment bacterial activities. Future studies will examine whether genes utilised for wood degradation are differentially expressed.