Bad luck with fish…

[sjk123]

initially I had 1 green chromis, 1 Kupang damsel and 1 Scooter blenny in a 100 gallon. All were happy and getting along no issues. 2 weeks ago purchased a lavender tang. Once he got settled he started attacking everything. After about 3 days i watched him kill the kupang damsel by crushing him in the corner. Immediately after he turned his attention to the chromis. The following morning the tang was no longer visible in the tank and was found dead between the rocks. No apparent reason as he was acting normal upon last look at tank.
The remaining fish are completely fine. Added 2 baby clownfish 3 days ago. This evening the chromis attacked aggressively and within an hour both clownfish were dead.

I’m getting really frustrated with the cycle of everything apparently killling each other. And don’t know what to do. Should I try to add a new damsel to counter the aggression of the chromis?

All water parameters are normal and the remaining fish again are completely healthy.

 

[rayadog]

So you have 1 chromis and 1 scooter blenny left? Do you quarantine? And could you? I would expect a chromis to be that viracious but I bet if you could remove them and return them as you add or after you add new fish; maybe even change up the rocks

 

[Ridgeback1]

I second the quarantine tank need--not just to keep out diseases, but also to let new arrivals settle in without stress of being instantly thrown into an established tank whose residents have territories already. Also, I have had success using an acclimation box. A few days in the box during introduction allows new and old fish to get used to each other without being attacked. Then after a few days, release the fish at night so it can find a spot to settle without being harassed. Some also use a mirror to occupy any boisterous current residents during introduction but I've never tried that. (The tang may have died from shipping stress (including ammonia toxicity) or disease but unclear until we know your quarantine practices, if any).