Fish used in these tests were the Israeli strain of the common carp, Cyprinus carpio; the Nile tilapia, Tilapia nilotica; the Java tilapia, T. mossambica; and the Congo tilapia, T. melanopleura. Israeli carp and either Nile or Java tilapia in ponds containing only these species virtually eliminated aquatic weeds, but when stocked into established populations of largemouth bass and bluegill results were less encouraging.