Hey! I have a medium-size tank and many plants there to recommend something based on my own experience. Azolla is one of my favorite plants because it Gives good shelter and shade to fish, and there are different colors. Cabomba Caroliniana looks very natural, and I like it. Floating Bladderwort develops bright yellow blooms and is harmless to inverts and fish. You can find more info in this study
, and I hope it will help you.