A total of 89 species of fish found in fresh and brackish waters belonging to 45 families is known in Negros and Siquijor islands. The most species rich is the Family Gobiidae (13 species) followed by the Family Eleotridae (10 species), Ophichthidae (six species), Cyprinidae (three species), and Poeciliidae (four species). The Families Muraenidae, Ambassidae and Mugilidae are represented by three species each and the Families Plotosidae, Syngnathidae, Terapontidae, Apogonidae, Carangidae, Lutjanidae, and Cichlidae are represented by two species each. The rest of the families are represented by only one species. Most of the species belonging to the Families Poeciliidae, Clariidae, Cyprinidae, and Loricariidae are all introduced species and brought to the country through the aquarium trade and aquaculture programs.