Vol.: (0123456789) 1 3 Biol Invasions https://doi.org/10.1007/s10530-022-02756-z REVIEW Nile Tilapia, Oreochromis niloticus (Teleostei: Cichlidae): a threat to native fshes of Lake Malawi? Jay R. Staufer Jr.  · E. R. Chirwa  · Wilson Jere  · Adrianus F. Konings  · Denis Tweddle  · Olaf Weyl Received: 28 February 2021 / Accepted: 10 February 2022 This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2022 native fshes of Lake Malawi. With Lake Malawi har- boring more species of fshes than any other freshwa- ter lake in the world, a loss of species diversity due to the introduction of Nile Tilapia would be catastrophic for this unique system. Native fshes that in recent years provided 70% of the animal protein consumed in the country would be threatened by the coloniza- tion of the Nile Tilapia. We are convinced that should the Nile Tilapia become established in Lake Malawi it would (1) Cause the extirpation/extinction of native fshes, (2) Hybridize with endemic Oreochromis spp., and (3) Damage the livelihoods of existing artisanal fshermen. Keywords Nile tilapia · Cichlidae · Fishing industry · Tilapia Introduction The introduction of non-native fsh species is a prac- tice, dating back to the Middle Ages, with the com- mon carp (Cyprinus carpio Linnaeus) being one of the earliest fsh to be introduced outside its natural range (Alves et al. 1999). Species introduction is a human mediated transfer of organisms into an area out of their native range. Fishes have been introduced both purposefully (Garcia-Berthou et al. 2005) and unintentionally (Copp et al. 2005). Unintentional fsh introductions often occur because of movement of fshes by humans or changes in the physical and/or Abstract The Nile Tilapia, Oreochromis niloticus, is a freshwater cichlid indigenous to the tropical and subtropical parts of the eastern and western Africa and is being cultured in the Lake Malawi catchment on the Tanzanian side. Historically, the Nile Tilapia has been successful in dispersing once it has been introduced into a catchment area. The probability of the Nile Tilapia successfully colonizing Lake Malawi is enhanced by many of its life history attributes including its fast growth rate, large size relative to native Oreochromis spp., and its diverse repertoire of feeding options. Where introduced, Nile Tilapia has had devastating impacts through competition or hybridization with native congenerics. We con- tend that the Nile Tilapia is a signifcant threat to the J. R. Staufer Jr. (*)  Ecosystem Science and Management, Penn State University, 432 Forest Resources Building, University Park, PA 16802, USA e-mail: vc5@psu.edu J. R. Staufer Jr. · D. Tweddle · O. Weyl  South African Institute for Aquatic Biodiversity, Makhanda, South Africa E. R. Chirwa · W. Jere  Africa Centre of Excellence in Aquaculture and Fisheries, Department of Aquaculture and Fisheries Science, Lilongwe University of Agriculture and Natural Resources, P.O. Box 219, Lilongwe, Malawi A. F. Konings  Cichlid Press, P.O. Box 13608, El Paso, TX 79913, USA