I have two zebra danios and it seems like on of them is a bully. One of them is always chasing the other one around. It is always the same one (Fishie II) who is doing the chasing. And the one being chased (Danny) will put up with it for a few seconds, then retreat down to the bottom of the tank where he can "hide" from Fishie II. Danny will stay down there awhile, but as soon as he ventures back towards the top of the tank, Fishie II immediately chases him back down again. Is this normal behavior for danios?
And would the behavior change if I added one or two more danios so they could "school"? I don't really want to, since I have such a small tank (10 gal), and I'd like to leave plenty of room for a few other types of fish. But I will add another zebra danio or two if it keeps Fishie II from chasing Danny so aggressively. Any advice?