Diploid and triploid grass carp externally look the same - identical. Some states allow only sale of infertile or sterile grass carp (triploids). The fish farm probably did not really mean the eggs will drown. Typically grass carp eggs require a fairly high current or strong enough current to keep the eggs suspended and moving in the water column (river) until they hatch. Under ideal conditions, I suppose fertile (diploid) grass eggs could hatch in a pond or lake's calm water setting, but this would be a very rare and an unusual situation.
Do you ocassionally see your oldest largest grass carp sunning, idly near the surface on warm sunny days?. Grass carp often "hang" in lose groups. If you occassionaly see them near the surface do you see smaller or intermediate individuals in the school of largest fish?
