I'm not sure if my 30g. wide is considered large enough for the betta to ignore other fish, but at the moment there are 5 rummynoses, 6 corys (3 julii and 3 sterbae [sp?]), and 3 snails. The betta isn't paying any attention to them so the tank size must be ok, he just won't swim around very much. Another thing I'm now dismayed about is that when the lights are on the rummynoses are staying at the very bottom of the aquarium and competing for space with the corys----when it's off the rummynoses are active in the mid-level area of my tank. Obviously they like a more dimly light home. I was so careful and researched a lot but it seems I didn't make very good choices. I want to see my betta, not have him stay in one little spot and rarely come out. IDK. I wish I could put in maybe 3 slower swimmers that are gentle and more "quiiet" than the boisterous corys and rummynoses, but I don't know what type of fish that would be.