I recently had to move my King Betta into a 5 gallon tank due to some tank mate issues. He is now living alone and is doing well. However, I have heard from some sources that King Bettas absolutely need a 10 gallon minimum tank and other sources say a 5 gallon is just fine. Is this 5 gallon tank okay for him or do I need to upgrade?? I attached a picture of Krypton in his tank. Thanks!!