Violence of genetically modified glofish It is said that these fish are not violent but that is not true We got one of these fish and it was in a tank with a similar sized lemon cobra guppy and in just about 36 hours this genetically modified glofish tore the cobra guppy to pieces we are away much of the time and thus did not monitor it right So the non violence claims are not true and like other GM fish e g salmon for some reason GM bring aggression