Help with Chromis Aggression / Tank Dominance

[CMO]

I've had two blue axil chromis for about 5 weeks now and they are becoming increasingly aggressive towards one another to the point that we lost a few scales during feeding last night. Also, while they are not overly aggressive towards other tank mates, they do dominate the tank and eat most of the food before the rest of the fish can get much (they even eat nori! - is this normal?). Just wondering if anybody has suggestions for calming these guys down aside from getting rid of one or both. I was think of maybe getting another dominate fish that might put these guys in their place without causing alternate aggression, but don't know what that might be, if anything. My yellow tang and kole tang are very passive. I'm feeding frozen twice a day (PE mysis, spirulina brine, and PE calanus) and nori a few days a week so everyone is well fed. My current stock list is as follows and all water parameters are on point and stable. Tank is 165 gallons.

1- Yellow Tang (medium 4-5")
1- Yellow Eyed Kole Tang (medium 4-5")
2- Black Axil Chromis (large 3-4")
2 - Wheeler Goby pair
1 - Blue Spotted Jawfish
1 - Gumdrop coral croucher (I hope.... haven't seen it since introduction :/)

Thanks

 

[cgdcinc]

I had 3 blue green chromis in with my coral beauty and melenuras wrasse. They were fine for a few months and slowly they started picking on each other. I’m down to one.
Some people keep multiples with no problem.

 

[PatW]

I had three green chromis in a quarantine tank. The one dispatched the other two in short order. It seems to me that aggression is less if there is some big, scary but non lethal fish present to keep the bullies from acting out their impulses. Easy to say and hard to accomplish.

I suppose one could keep green chromis well in a very large tank with some big imposing fish to over awe the chromis.

 

[DeniseAndy]

They may not work together. Most damsel family fish are not happy with similar genus and fight continually to death till one is left. Sometimes a pair. I would trade them back to store and try something more passive. In a 165g, you should be able to get a nice wrasse in Halichoeres genus or multiple fairs or flasher wrasses.

 

[CoralNerd]

I knew multiple chromis would pick each other off but didn't realize the one blue green chromis I had would pick on my Purple Queen Anthias. As of this morning I caught the chromis and it's out of the tank. Nobody better lay a hand on my queen lol

 

[mta_morrow]

Chromis tend to work out best singly, or in large groups - 7+.

In a large group aggression is dispersed among many vs a few.

Another thing to do is increase the flow in the upper area of the tank where they tend to be.

Some of this is from personal experience (from 3 to 1 in my first tank) and some from the success of others.

I currently have 1 in my new tank and it just does its thing and doesn’t bother anyone.

 

[CoralNerd]

Even better advice is pass on these fish. I have tons and tons of current, all these things are general advice that's been repeated on the forums.

 

[CMO]

Thank you all. Sounds like the best course of action is to re-home one.

 

[Lovell]

I purchased 2 chromis yesterday and even in the bag while allowing to acclimate the bully in the smaller bluish one started on the other. after i released them in the tank he swam a few circles and went to work on the other one scaring him into paralysis it was a wash $ down he goes...went back to the same store got a bigger one seem to be more challenging but no spunky the name i called the small bluish one now saw him in the bag floating in the tank after i let him out spunky was ticked went from green to blue and started brawling him. now i have the new guy quarantined i'll take him back tomorrow thanks Spunky your the winner...plan on adding clowns later i hope there's not a problem....Spunky green/blue chromis 2 -0

 

[Lovell]

I purchased 2 chromis yesterday and even in the bag while allowing to acclimate the bully in the smaller bluish one started on the other. after i released them in the tank he swam a few circles and went to work on the other one scaring him into paralysis it was a wash $ down he goes...went back to the same store got a bigger one seem to be more challenging but no spunky the name i called the small bluish one now saw him in the bag floating in the tank after i let him out spunky was ticked went from green to blue and started brawling him. now i have the new guy quarantined i'll take him back tomorrow thanks Spunky your the winner...plan on adding clowns later i hope there's not a problem....Spunky green/blue chromis 2 -0

 

[CMO]

Lol. Yeah. I think one or a large group is only way to go. Two or even a few don't seem to last. I got rid of one a while back and the remaining one is happy and calm now.

 

[pezcadoazul]

They may not work together. Most damsel family fish are not happy with similar genus and fight continually to death till one is left. Sometimes a pair. I would trade them back to store and try something more passive. In a 165g, you should be able to get a nice wrasse in Halichoeres genus or multiple fairs or flasher wrasses.

In nature chromis shoal in large groups. I had 7 in a 100 gallon tank for a couple of years with no problem. Then one disappeared without a trace. A few months later one began to hide in the rock work and would dart out quickly to eat. It then started saying in the upper rear corner of the aquarium by the intake for the overflow and would be in an almost vertical position. I thought it had swim bladder disease so put it in an isolation tank. Within a week it seemed to be perfectly healthy and was swimming and eating normally. I returned it to the main tank. It swam with the other chromis and I thought everything was fine. A few hours later, its tail and dorsal fins were torn and ragged and it couldn't swim. I euthanized it. Just today, I had to place another chromis in the isolation tank as it was being bullied and was swimming oddly and not eating. After a few hours of being isolated it seems fine. I am not sure what to do. Some people say that mortality is reduced if you maintain a larger group - 7 or more, so the chromis on chromis aggression will be spread around to multiple conspecifics rather than targeting just one. I want peace in the tank so I can look at the tank and relax.