ichthyootoxin UK /ˌɪkθiˈoʊ.əˌtɑksɪn/US /ˌɪkθiˈəʊ.əˌtɒksɪn/ noun1 •Any poisonous substance found in the roe or gonads of fish, but not in other parts of the fish.Asano and Itoh (1962) have investigated the chemical nature of this ichthyootoxin and found it to be a lipoprotein which they designated as “dinogunellin.” — 1965 formsichthyootoxins