I have always kept my betas in a little 1 gal or a vase and changed the water out once a week, I treat the water and keep it in the same room as the beta is kept so it is room temp and I have had 2 betas live more than 3 years each, just need to make sure it dosent get too cold in the room they are in and clean the tank every week, if you are keeping it at work just make sure he gets fed every day. Hope this helps

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10 gal with 1 molly, 3 red blue tetra, 5 male guppies, 1 zebra danio (has a hunch back was a rescue), rubber lipped pleco, 2 ghost shrimp, 1 tiger snail, with 2 live plants, 2 betta in seperate tanks