Molly Gone Mad

[Chri$]

i have had my tank setup for over a month i started with a couple of platys, one which died but the other lives on. the other day i bought a speckeld molly and another platy, just today the molly has started chasing the 2 platys around the tank and it looks like it's attempting to take lumps out of them.
Is this just play, a sign of an illness or just common behaviour.
thanks in advance
chris

 

[prankster705]

How big is your tank??

 

[Chri$]

60 litre
about 14 uk gallons