Chromis & Blennies

[Madreefer]

Originally Posted by michika

Chromii/Chromis kill each other off eventually. And they don't school unless something elicits the schooling behavior - usually a larger fish or something to trigger schooling behavior. Don't get me wrong, they're great fish, but they seem to die off when in groups until only one or two are left standing.

I have read the same thing. 6 months ago I put 9 chromis in my tanks and they schooled right away. There is no fish in my tank that pesters them. All 9 are still alive and make a cool looking school. I'm sure as time goes by they will start picking each other off.

As for the spare 20G i'd leave it as a quarantine. Having 2 tanks is a pain. And your plan of transfering fish from that tank to a sump when needed is too stressful for the fish.