Farmed fish can be healthy for humans, if grown under strict supervision. Sea food is one of the healthiest food to eat. Farmed fish means that they are grown in clean water and right kind of foods. A clean environment for fish would be healthy for fish, that will make the fish healthy to eat.
No, farmed fish are not unhealthy for humans, because they have the same nutritional content as wild fish. Farmed fish enjoy a similar quality of life as wild fish, and their diet can appropriately be managed by care providers. There are no demonstrated health risks associated with fish that is specifically farmed, so it is not unhealthy for humans.