What can put???? the filter is on slow but in minuts filters the whole tiny tank

I would have cories or divide the tank and get another betta.

Is the tank a 3g or 10g?

If you have a male betta, I would take a long look at his disposition before you put him in with any kind of fish. I would personally if I had a 10 gallon tank get a few brightly colored females. I keep my males all in separate 2.5 gallon tanks with filters.

I would not put anything else in there. 3 gallons is a good amount for a single betta, but not enough room to add anything else. Bettas don't like a lot of water movement...are you sure the 10 gallon filter isn't stressing him out? What brand is it? A smaller filter would be more suitable for a small tank, especially with a betta.

I must have read your post wrong, sorry. If its a 3 gallon you should not put anything else in.

hi here is a good article about what fish are compatible to a betta in community tank .Good luck
http://www.healthybetta.com/articles/Commu...ldcommtank.html