Healthy foods such as fish can be raised a controlled environment and will provide healthy fish to be consumed by the public.The only problem is that it is not cost efficient. There must be employees trained to monitor water quality and oxygen allotment available in the water as well as many other conditions. The cost could be staggering.
While it's entirely possible to wipe out a population of fish by harvesting from it too aggressively, there are many instances of people finding the correct balance to keep the population where it is while still benefiting from what it has to offer. Outright banning fish farming punishes everybody because of the irresponsible few that don't care about what they leave in their wake for a few extra dollars.