When I had my cats in a 55gallon they would swim all over, I could power feed them and everything. Since I switched to the 180gallon many months ago and now they just seems to hover in the corner farthest from the light. And they seem to hate being by other fish. When I feed them the littlest guy grabs the food but if a fish gets to close he runs. The bigger guy just doesnt go near the food if any fish are near by. They are about 5" and 7". Could this be a case of not enough of the same species to feel good?