10. A fish has suddenly separated
itself, hanging in the upper corner of the tank.
Keep a close eye on the effected fish, if things
don't calm down after a week or so remove the stressed fish and find it
a new home.
Whenever a fish separates itself from its tanks mates it's an
indication of a stressed fish. If the fish is hanging in
the upper corner chances are its being harassed and chomped on
by a grumpy mug like the Frontosa in the picture.
Compatibility in a community tank can sometimes be tricky.
Even fish that are generally compatible can fight during
spawning or just to show who's the boss. Rearranging the
decor in the aquarium is sometimes enough to calm things down.