They will not survive. I think if I raised thousands and millions of these fish and returned them to the wild, next year, there would not be any more than there is now..... All things are limited by their environment, and in this case it is a polluted filthy ditch with eels, goldfish, gambusia and inanga also living in it. Now that You've got me thinking about it, if I could remove some of the goldfish in there, that would be a good thing... unless you are a goldfish, that is.