Experience with firefish & purple firefish?

[Ruth]

I started out with 5 purple firefish (added at the same time) in my 110g cube (lots of live rock and caves etc for hiding). They were fine for about 6 months then started fighting amoungst themselves.
I now have only one left and he has been alone for about 8 months now.
I have found that as they mature they tend to get more territorial - also they are jumpers so as they do become aggressive they will chase the other fish right out of the tank.
Just my experience.