Chromis School
 

Hey guys i have a question about keeping these fish in numbers.

I have tried in the past to add 6 chromis into my tank however the "bully" in the group seems to take over and nip at the others until he takes out one after another.

I tried once again (8 months later) to add 5 other chromis to the tank but the bugger has taken out all but one which more than likely wont make it another week. My question is if i move or get rid of this current 'bully' and try adding a new school of 5 or 6 chromis would i have better luck keeping a group of these fish? or am i to assume one will become once again more dominant than the others and the record will play over again? Thoughts?

I have seen this done in large tanks, assuming your tank is the 33 gallon in your signature I wold say your always going to have this problem. In our 180 we had problems keeping a school as the aggressive one would eventually take over.

see.....the problem isnt with the chromis......the problem lies with what the majority of people think is a school.....we add 6, or 10, or 20 "schooling" fish and think we have a school.....these fish school naturally in numbers far larger that we aquarium enthusiasts could ever hope to house......what we have when we add 10 chromis, is a small group, so what usually ends up happening is you end up with significantly less than what you started with, after one fish establishes dominance........another factor is the lack of presence of large predatory fish(or perceived to be predatory), keeping the schooling fish feeling the need to school......

Chromis
 

I read somewhere to keep them in odd numbers. 3-5-7 ect...Not sure why but seems to work for me. I have 5 in a 90g reef and no problems. I actually took two out and put in my other tank(100g) and the three had no problem and the two together did seem to fight a little. I put the two back in the 90g and the other 3 seemed so excited to see them. Swimming around like crazy and "greating" them. No problems at all.
They are green chromis by the way. I was thinking of adding some blue chromis to the mix to see what happens.

^ very interesting.

Well the first time i added a group of chromis was a month or two after buying this tank second hand along with no knowledge of saltwater whatsoever so i assumed the lost fish could have been the cause of bad water parameters. Now that i have a basic understanding of water chemistry (12 months almost to the day!) i figured it may have to do with behavior and dominance. Thanks for the comments guys, i think ill be holding off on trying this one again until i have a much larger tank.

funny you mention that because i recall reading something very similar awhile back. However i guess 33 gallons isnt enough to keep these guys happy.

Numerous small feedings throughout the day will help lower the aggression.

I totally agree that what we consider a school is really just a small group, comparatively. That being true, a small group of no less than 6 can still exhibit schooling behavior in an aquarium if their needs are met.

I have kept a group of 6 happy and healthy for a couple years(before total system crash) and now have 2 groups of 8 for several years (in separate tanks) that both spawn regularly.

I attribute my success to 4 basic requirements: plenty of space (maybe no less than 100 gal for 6), decent water quality, regular and frequent feedings, and lots of flow (only times I have been successful was when running Tunzes).... well, maybe 5 requirements.... they also need coral they can hide out in.

Hope this helps.

400 gal
 

I have kept a "school" of the same 15 or so chromis successfully for over 2 years which breed & spawn like crazy but it is very difficult to achieve good results with a smaller tank.

I have had 13 or so in a 130g. They never school together like I thought they would. They usually hide behind rocks, powerheads, etc, separately. They are now down to 7 after two years.

I read somewhere they like to graze all day long on tiny planktonic foods, and since then, I have fed them with freeze-dried cyclopeeze, "Reef Chili", Acan Plus, and even Combo-vital.
They do love picking these food off the surface and water column.
HTH.Lenny.