Thank you all for your suggestions! My pH is 74, kH 2, gH 4. I would definitely prefer to get a 4"-6" fish (my bettas live in 2ft long 15 gallon tanks, I like my fish having more space lol) but the tank is in the living room so I'll have to stick to a 6"-8" fish since it's not solely my tank. I'll look into the suggestions and see which fishes will prefer my water parameters and that my parents like the look of!