I also keep Blue/Green chromis in schools. I have an 8ft 600g DT that I restarted in March of last year. I began with 12 but lost 4 in the first month or so, that I believe was due to unhealthy fish (one of my last purchases from LA ). I've had 8 now for about 9 months and no aggression to speak of. I'm planning on "QT-ing" 6 more next month and adding them in March.