Some species of crayfish may build burrows that can cause problems in your pond. Currently, there is no approved pesticide labeled for use on crayfish in ponds. Remember not all species of crayfish dig burrows and fish like largemouth bass and channel catfish will feed on them. There are several "home remedies" that can be used but are not recommended near your pond as they are harmful to fish. Remember that any insecticide that you may use will kill your fish, always read and follow all label directions.