Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations Grass Carp, Does this make any sense ?

Yup, those nasty plants are not even on the grass carp's menu. In fact, those carp could be helping those plants by eating other not as bad plants that compete for the same nutrients. And Tilipia would help only with dw if the bass and cc did not eat them first. Each plant is going to need to be dealt with seperately. I don't think biological control with fish is going to work for you here.