 nov. "argens"" as extinct in the wild, and six species are listed as entirely extinct, but it is acknowledged that many more possibly belong in these categories (for example, "Haplochromis aelocephalus", "H. apogonoides", "H. dentex", "H. dichrourus" and numerous other members of the genus "Haplochromis" have not been seen since the 1980s, but are maintained as Critically Endangered in the small chance that tiny –but currently unknown– populations survive).Because of the introduced Nile perch ("Lates niloticus"), Nile tilapia ("Oreochromis niloticus"), and water hyacinth, deforestation that led to water siltation, and overfishing, many Lake Victoria cichlid species have become extinct or been drastically reduced.By around 1980, lake fisheries yielded only 1% cichlids, a drastic decline from 80% in earlier years.