I've noticed something about tropical fish people over the years. All of them are rabid animal lovers. Lovers of every and any kind of animal. I am still hung up on the Bearded Dragon lizards I want but have not yet acquired. Someday.
@PheonixKingZ is right. It's not the animals that have escaped into wild and were fruitful and multiplied that are the problem. It's irresponsible people. Many people want some pet as a spur of the moment whim and soon tire of it and, feeling sorry for it, they set it free. Tropical fish people are different. It takes a lot of effort and time to set up an aquarium and have it work. Those people take care of their animals properly.