Farms are often crowded and prime locations for parasites. Fish farms are notorious: https://www.thetimes.co.uk/article/supermarket-salmon-riddle...

Parasites are no problem as long as you cook the food properly.

Farmed animals have a tendency to be a mono culture that is housed on way too little space which is a breeding ground for problems that then need to be controlled by heavy use of pharmaceuticals which is detrimental to human survival.

Think anti biotic use in chickens for example. And the resistances that come with it. And fish tanks that do exist already have some of these issues already as well. How expanding that even more is a good thing is nebolous to me.

Also the animals may not like it.