Hello, I am making a community fish tank and so far I have a blue mickey mouse platy and these platys that look like a sunrise. My question is, two of the fish look like their stomachs are caving in, their backs look crooked like the shape of an "s." They shimmy a lot and they eat little. The other fish in the tank seem to get to the food faster than they do. what is going on? how do I ensure they get ample food? is that the problem?