Corydoras
Hello Violet...
Your corydoras (little cat) won't get too large. I have some that are close to five years old and they're a little more than 2 inches long. I keep quite a few of these little guys in my tanks. I stock one for every five gallons of tank volume, so you could have three or four more of various kinds to keep your fish company. The Corydoras don't have to be the same species to get along, but they do better with others of their kind. They're all very peaceful fish.
B