Hello ver...
Good luck with your Orandas. They're supposed to grow to close to 10 inches. Yours, in such a small tank, probably not. But they need large, frequent water changes. If you change half the water in your 20 G every two to three days, that wouldn't be too much.
I keep Comet goldfish. They're quite a bit smaller and I have them in a 38 gallon tank. I have a lot of plants too. I keep Anacharis, Hornwort and Anubias in my Comet tank. It's a good food supplement for them. They also like Duckweed.
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