One of my male cherry barbs has become very territorial and chases off other cherry barbs and julii cories. He has claimed the lower level of 2/3 of the 29g tank, reducing the cherry population to 1/3 of the tank and constantly chasing the juliis around. He doesn't bat an eye to the dwarf gourami or upside down cats though. Of the cherry barbs, there are 3 males and 5 females. He has been like this for a couple weeks now, but previously all of the cherry barbs were peaceful and the rest of them still are. Everything else in the tank is perfectly normal. Any ideas why this one is suddenly choosing to go solo and chase everyone out of his territory? Do some cherry barbs get aggressive/territorial like this? I know when mating they can be more fiesty, but he's more than just fiesty and isn't even full red like they usually are when ready to mate. Just trying to figure out what's going on with this guy.