I don't think you can, but someone else may be able to help you more. Since you have a huge tank, you can try putting snails or ghost shrimp in with him. Those are the ones I know should be okay with him in that size. Though snails produce a lot of waste. As long as it's kept clean, it would be fine!I know there are some schooling fish that people keep in large tanks with a betta, but I don't know enough on that to give you a fact answer.
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