These two species both from Asia are really taking off in the Mississippi and Ohio river drainages.  One bighead taken from the upper Ohio River was 47 pounds, possibly a world record.  Animals seems to grow larger in a new environment without factors such as predation and diseases acting on them. The carp are mainly feed on phytoplankton and algae.  Therefore, they may be competing with the native paddlefish and other organisms depending on algae such as mussels.