help! need opinions on what to do.

[annnie]

hi,

My betta has become very horrible to my corydoras lately and is always harrassing them. Today i found a big chunk of dorsal fin missing and definatly think it was mr betta!. I want to move all my catfish into the only other tank i have which is being occupied with guppy fry. Half of the original amount of fry i rescued where infected with Flexibacter columnaris and died but i havent had any deaths for about a month. Will my injured cory contract columnaris if i put him in the fry tank?. i read that it is always in tank water and will attack when the fish is stressed so is it better to put the corys in the fry tank or keep them with the angry betta?.

The betta used to be ok so but now hes a grump.

anyway thanks for any advice!,
annie