shell dweller agression

[dr_girlfriend]

I had always read that shell dwellers were not agressive, just a little territorial and could get in little tiffs. I have 3 calvus' and 2 l. caudo's in a 10 gallon. Both species kind of stuck to their own side for awhile, but recently one of the caudos has been beating the crap out of everyone especially one of the smaller calvus'. It got to the point that I had to take the calvus out and put him in a 1 gallon tank for treatment before he was killed.
I've been observing the behavior and it seems that this one caudo is the dominant male and the rest are extremley submissive to him. I am planning on moving them to a wider tank, I was thinking even perhaps a turtle tank for more territorial space. But if that doesn't help I'm not sure what else to do except perhaps remove the dominant male.