The relationship between feeding preferences and consumption rates in grass carp and grass carp × bighead carp hybrids

The relationship between food preference hierarchy and consumption rate was examined for the grass carp, Ctenopharygodon idella , and its Fl hybrid (grass carp × bighead carp). Preferences of both types of fish were similar, although hybrids consumed vegetation at a much lower rate. For both, relative preference in feeding trials with mixed plant species was significantly correlated with consumption rate in monospecific feeding experiments. No correlations were found between preference and caloric content, protein content or relative water content. The hypothesis is proposed that preference hierarchies reflect relative handling times of different food types and that these fish maximize 'through-put' by preferentially consuming plant species which can be most rapidly ingested.