Under ideal conditions, grass carp may consume 2 to 3 times their body weight in plant material per day and gain 5 to 10 lbs per year. The fish may grow to 4 feet in length and weigh up to 100 lbs in their native waters. However, these fish rarely exceed 30 lbs when harvested from ponds. Large grass carp become very active when trapped in a seine and can be dangerous to handle. The fish will not feed when dissolved oxygen is low.
Many states allow the restricted use of grass carp for aquatic weed control.
Triploid grass carp are not capable of successful reproduction due to an extra set of chromosomes. These fish are permitted by many states as opposed to the diploid grass carp which have two sets of chromosomes and are physically capable of reproduction. Successful spawning populations of introduced diploid grass carp have been reported in the lower Mississippi River and some rivers in Mexico. The triploid fish is produced by either temperature or pressure shocking the fertilized egg during its maturation process. A coulter counter which is a electronic particle size analyzer, determines the larger triploid fish blood cells from the smaller diploid fish cells.