Ornamental fish in the South African pet shop trade: potential risk to natural aquatic ecosystems

The aquarium pet trade is one of the leading pathways for the introduction of invasive species into natural ecosystems. In 2018, we surveyed pet shops across South Africa to obtain a checklist of ornamental fish species in the aquarium pet shop trade and to assess their invasion potential using sourced data (e.g., natural environment, native range, introduction status, impact status and climatic zone). We evaluated selected common aquarium fish species with high invasion potential according to previous invasion history. We highlighted the need for the development of a management strategy for the aquarium pet trade in South Africa. We identified 312 fish species belonging to 77 families and 182 genera. Most pet shops were in Gauteng Province (n = 38), with few in Limpopo Province (n = 3). Gauteng had the highest number of fish species (n = 271), while North West Province had the lowest number (n = 95). Pet shops were dominated by freshwater species (68%), followed by marine species (22%), while the origin of 30 species (10%) was transitional aquatic ecosystems. Most freshwater taxa were native to South America and Asia, while most marine species were from the Pacific and Indo-Pacific Oceans. Most (88%) species were tropical, 10% subtropical, and 1% temperate. Several (n = 28) species had more than 50% frequency of occurrence, representing the most popular ornamental fishes. Several (n = 13) species are invasive in South Africa and other parts of the world. The system of importation of ornamental fish in South Africa is not clear. Although there is a recommendation that these importations must be regulated according to the whitelist and blacklist in South Africa, it is not clear how this is implemented in practice. We demonstrated a high risk of alien fish species introduction in South Africa through the aquarium pet shop trade.