This is common for allot of fish. I find it evident in my aquariums in the
evening when the tank light goes out for the night and I sit near my tank
with my reading lamp on the fish seam to roll over on their sides and swim
along the front glass.


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.483 / Virus Database: 279 - Release Date: 19/05/2003