I have had these cats (2) for three years now. I started them out in a 10 gal
then moved to a 25. They grew up to 4" and have stayed there now. They are in a 55 now, so maybe they will get a little bigger. So tank size to begin with is not an issue to begin with. They do like the room to swim in, but stay pretty much hidden until night time, that's when they are most active and looking for food. If I could sell them I probably would as I have outgrown them as an Aquarium fish, As I said, they are for the most part an inactive fish, and I prefer a more active swimmer in my tank.
Running 4 tanks; 5 soon
One 55, Two 25's, and two10's, adding a 75 for Oscars