A couple of years ago I caught some tiny minnows (probably Notropis procne, the swallowtail shiner) at a local pond and put them in my tank. At the time they were about 1 cm long. One of them, I named "Stumpy" because most of his tail fin was chewed off. He was so skinny his stomach was concave, and, if that wasn't bad enough, his spine was crooked. He could hardly swim, and when scared, used to hide at the bottom of the tank in the corner. But at feeding time, he would struggle valiantly to get the food, in spite of having trouble swimming and the other fish snapping up all the food. Now, two years later, his tail fin has since regrown. He still has a crooked spine, but is now about 8 cm long, has a big fat belly, and doesn't let the other fish push him around.