Ensiled fish contains a considerable amount of the
free amino acids that constitute the precursors for
biogenic amines such as histamine, tyramine, putres-
cine and cadaverine (Haard et al., 1985). Biogenic
amines are formed by decarboxylation of their
precursor amino acids, as a result of the action of
either endogenous amino acid decarboxylase activity
(Halasz et al., 1994) or by the growth of decarbox-
ylase positive microorganisms (Halasz et al., 1994;
Silla Santos, 1996). The low pH (below 4.5 after 2
days of fermentation) and the physical characteristics
of fish silage that lead to a low oxygen concentration
within the ensiled fish are favourable for the action