So right now I have a 17-gallon tank housing a male betta, 2 corydoras, 4 Cardinal Tetra, and a few shrimp. It's pretty well-stocked I guess. The betta stays on the top, the tetra in the middle and the catfish on the bottom. And I'm wondering- should I add more fish? I'm thinking of a pleco or some other small schooling fish to add in the tank. Much help would be appreciated. Thanks!