Bettas defend their nests and the small surrounding area, in a 10 gal it my be a hit and miss thing but in a 1000gal+ pond you could have quite a few, I had two in my 55 and they didn't even know the other existed.moxxommox;820047; said:they have done some study, even in a large pond, talking 1000gal+. 2 fish sill will seek each other out and fight, it's not aggression its just pond domination.