I agree with choclatebetta, that hole could present a problem, best keep it covered, I had a male jump through a 1cm round hole before. I couldn't believe it, he jumped into the tank next door and battled with the betta next door all day (I was out). The other betta came off worse and had his bottom jaw ripped off and had no fins left, despite the grievous injuries his fins fully regrew and his jaw was always crooked but he never missed a meal. Obviously the main concern is that he will jump out and suffocate. If you decide to use this tank just be sure to keep that hole well covered