With a 10 gallon tank and no smaller you could be able to put 3 Corydoras catfish in with your Betta, but I will say that the last few folks that I have heard of that have put Corydoras in with their Bettas have had less than stellar results. But it may have been the Betta and his personality and if you decide that Ace is pretty docile and laid back then perhaps it would work. Keep in mind though that you will have to have at least 3 Corydoras to make them happy and if you are going to have Otocinclus in that large of a tank they need at least 3 in their group also to meet the needs of the tank. I have personally had luch with Otocinclus but my tanks are not large enough for Corydoras and so some of the others may wish to address that issue.
It is going to make a difference that Ace has already bee established in the tank and you will be adding the catfish. I think the Otocinclus are much more tolerant of the stress of being chased and hassled and all than Corydoras are. I believe that Poefox has had some who were literally scared to death with all the bullying.
Rose
