Lots of stuff you could put in that. Betta, shrimp, microrasboras, swampfish, pygmy sunfish, least killifish, bluefin killifish, rainwater killifish, and a few others. People always underestimate the possibilities of small tanks.
OK so after doing reading and....stuff I came to the conclusion that I NEED A FILTER! I can't tryst the plants too much, I feel like they might screw me over at some point