Fermentation ensiling of fresh water fish viscera with 10% (w/w) molasses, 0.5% (v/w) propionic acid and 0.02% (w/w) ethoxyquin at 26+/-2 degrees C and 37 degrees C was investigated The pH values and reducing sugar contents were significantly (P less than or equal to 0.001) lower and lactic acid contents higher (P less than or equal to 0.001), in mixtures fermented at 37 degrees C than those fermented at 26 degrees C. Coliforms, Escherichia coli, enterococci, staphylococci and salmonella were absent from 48 h or 72 h onwards in fermentation at 37 and 26 degrees C. Clostridium perfringens was absent after 48 h, and spores after 72 h, of fermentation at both temperatures. Markedly lower (P less than or equal to 0.001) bacterial total viable count and marginally lower (P greater than or equal to 0.05) yeast and mould counts were noted in samples held at 37 degrees C. Lactic acid bacterial counts were higher initially (up to 48 h) at 37 degrees C than at 26 degrees C. The ensiling was thus faster at 37 degrees C than at 26 degrees C. (C) 1997 Elsevier Science Ltd.