black carp still consumed a wider size spectrum and higher quantity of apple snails than common carp. Both fish were unable to feed on large-sized apple snails, but their long life span of up to 13 years (Nico et al., 2005), their ability to consume larger apple snails as the carp grow, and the high natural mortality of large-sized apple snails (Kwong et al., 2010) should make both species of carp effective bio-control agents in Asian freshwater wetlands. Compared with common carp, however, black carp ap- peared more beneficial as it preys on invertebrates only, whereas common carp feed on both invertebrates and macrophytes.