Question re interesting behavior

[carbaryl]

Hi,

I have a 55g tank with 8 cobalt blue juveniles ranging between 2.5-3.0 inches. Yesterday, I added a young pigeon blood of about 3.5 inches. After a couple of hours of acclimating, I noticed it was facing nearly vertical in the tank. I was concerned, thinking maybe I did something wrong while introducing it, but when I looked more closely, I saw the largest blue "nipping" at the pigeon blood's head and flanks. The latter didn't seem to mind, and soon was swimming around the tank normally, eating with the others. However, I saw this behavior repeat itself several more times that evening. It looked very much to me like a cleaner wrasse tending a host, the pigeon blood really looked like it was in some sort of trance. Obviously, the blue was too large for this to be some sort of "nursing" behavior, and I would think they are all too young for this to be courtship (would that even occur so early after introducing the new fish?).

Is this a typical behavior? Was the blue feeding? grooming? All is well this morning, so I assume everyone is still healthy.

Thanks in advance...

Jeff

[Merrilyn]

Welcome to the forum Jeff.

It is quite normal, if fairly unusual behaviour.

I've had fish that have done that before, but it's always a bit of a surprise, and I've wondered if it was a case of picking on a weaker fish, but I've come to the conclusion that's it's harmless behaviour, although I've never been able to figure out a reason for it.