Fluorescent protein transgenesis has varied effects on behaviour and cold tolerance in a tropical fish (Gymnocorymbus...

Fluorescent protein (FP) transgenesis is used in the ornamental aquarium trade to produce new colour morphs in tropical fish. Understanding whether such genetic modification could alter ability to survive temperate waters, or interactions with native fish, should such fish be released to natural systems is critical in developing policy on their commercial use. We examined the competitive foraging ability and cold tolerance of unrelated pet-trade sourced adult green FP transgenic tetra and non-transgenic white tetra (Gymnocorymbus ternetzi), as well as white non-transgenic and green FP transgenic juvenile progeny of these groups. FP transgenesis did not affect the foraging success or aggressive behaviour in either adult or juvenile fish, indicating FP transgenesis may not influence potential hazards through this pathway. During a cold temperature tolerance trial, adult green tetras had greatly diminished cold tolerance relative to unrelated adult white fish, while sibling juvenile offspring of these groups had intermediate cold tolerance between adult fish groups that were not affected by FP transgenesis. This data suggests background genetics, rearing history and/or life stage may play larger roles in cold tolerance than FP transgenesis in this species. Unexpectedly, both adult and juvenile white tetras were 3.8 times more likely to take refuge in shelters when temperature declined than green tetras. These data indicate FP transgenic fish may pose equal or lesser risk than non-transgenic fish, should they be released to natural environments. Results also demonstrate that unrelated pet-trade sourced fish may not always be appropriate models for examining effects of FP transgenesis.