I can recommend wild caught fish from overpopulated lakes (usually caused by eutrophication from nearby farming, including fish farms). Overpopulation and invas

I can recommend wild caught fish from overpopulated lakes (usually caused by eutrophication from nearby farming, including fish farms). Overpopulation and invasive species usually share a few common trait: Low commercial interest, caused by human actions, and not enough focus from environmental friendly policies. Here in Sweden it seems like most freshwater lakes suffer from overpopulation, and the commercial value of the fish is so little that the transportation cost to cat food factories makes it unprofitable to fish it. Making matters worse, overpopulation in lakes has a tendency to cause extinctions where some species crowds out others. There was/is some government initiative to fund fishing directly, but so far very few has taken up on the offer. It is however quite hard to find a seller for this. Some restaurants has made a bit of PR from saying that they are serving this kind of fish, but I have never seen a menu with it or seen those species in any store. Your best bet would be to buy it directly from those fishing in the lakes which could be problematic depending on where you live.