Hmmm...strange - I know that my two dalmation sailfin mollies can get extremely possessive over food and can get quite bullying - but I've never known them to actually take chunks out of another fish or cause any actual harm, it's usually just chasing and a bit of nose-butting.
Did you actually see the mollies attacking the sharks? Just wondering because you say you have a red-finned shark in there - I know that the rule of thumb is not to mix different species of shark in the same tank as they will attack each other and cause deaths. If it's a large tank then sometimes you can get away with it as they will each claim a section of the tank as their territory and only fight when that is invaded.
Could it be that adding the mollies to the tank has upset the territorial boundaries a little, that both sets of sharks then had less of a boundary and it's caused some unrest in the tank?
ps - In your post on the other forum thread you say your tank is 25gallons, was that a mistake?
Edited by Athena, 25 September 2008 - 01:06 PM.