I don’t have any plant advice right now but I saw that you have two comet goldfish with a betta in a three gallon tank. I feel this is a lot and they aren’t good tank mates. Goldfish also need more room to move around. The amount of waste produced would require a weekly
WC. This is an acceptable size for a betta to live by itself but not to thrive in. You could do weekly
WC but it would stress out your betta but if you don’t do it weekly the fish could get ammonia poisoning. Another thing is goldfish are fin nippers, a bettas worst nightmare. Ghost shrimp would do great in your tank as I know you already have them. But in all it’s a bad idea for the betta and goldfish. Correct me if I’m wrong on anything.