Old chromis introduced to little chromis??

BigBearMD · Apr 12, 2018

I’m curious to everyone’s thoughts.

I have an older chromis, let’s say a year and a half old, and it’s pretty big. This one is swimming around in my 30gal frag tank.

I have three new chromis, maybe 3 months old, and still pretty small in my 180gal DT tank.

I’ve been considering moving the old guy into the DT so I have one less thank to feed. Particularly with many summer trips coming up, I’m trying to simplify my tank chores for the pet sitter.

I’m a little worried about aggression. Any thoughts?

sfin52 · Apr 12, 2018

There will be a bit of a squabble. If I where you I would add five to six. This would spread the aggression over more fish and lessen the aggression for all. I had two in my tank and added three more all has been peaceful for the most part. I do see a hierarchy in my 5 bgchromis.

Dr. Reef · Apr 12, 2018

You will end up with 1 chromis eventually and most likely 1 that is the oldest and biggest.

sfin52 · Apr 12, 2018

I have had mine for 3 years. Still going

tripdad · Apr 12, 2018

I've had my group for two years now, stable. Use odd numbers and only 1 dominant fish. The dominant fish will show different coloring than the non dominant ones do.

Soopa1 · Apr 12, 2018

Just did the same thing a few months ago. Added four small ones with an already established bigger one. I now have only one of the four left and the bigger one.

BigBearMD · Apr 13, 2018

Thanks. Basically the answer is no.

I already started with 5 and I am down to 3 on the small ones.

Tahoe61 · Apr 14, 2018

Feeding them small amounts of food multiple times a day appears to cut back on the aggression.

DeepBlueSomething · Jun 7, 2018

So I came across this thread -- excited after adding two small chromis to my 40b tank (Saturday 6/2) . Both happy and no apparent issues with the mela wrasse or the 2 mocha clowns. Everyone was eating and didn't see any aggression during feeding or otherwise...the chromis were housed together at LFS

And then last night, I came home to 1 dead chromi. No signs of illness -- just a significant wound near his tail. He was fine at the morning feeding and then...toast.

My question -- who is the likely culprit? My wrasse is happy to take out snails and hermits at his whim. I never would have assumed it was the other chromi until I saw this thread...

JohnPeck · Jun 27, 2018

Dr. Reef said:
You will end up with 1 chromis eventually and most likely 1 that is the oldest and biggest.

How does this happen? Will it be the stress or will one actually kill the others? Down to two but today one was hiding and breathing heavy and all of a sudden the other one looked much bigger. I liked having them together.

Dr. Reef · Jun 27, 2018

Its not set on stone but in my almost 3 decades of experience some websites and lfs will tell you they school or can be kept on groups.
Yes maybe for few reefers but in my long term experience the whole family ( clowns, chromis, damsel) will eventually kill each other off till only 1 or 2 left. It May not happen right away but over time they develop territorial aggression and will run off others either by chasing them out or physically beating them. In either case stress or fight both will lead to death on smaller less stable fish.

JohnPeck · Jun 27, 2018

Dr. Reef said:
Its not set on stone but in my almost 3 decades of experience some websites and lfs will tell you they school or can be kept on groups.
Yes maybe for few reefers but in my long term experience the whole family ( clowns, chromis, damsel) will eventually kill each other off till only 1 or 2 left. It May not happen right away but over time they develop territorial aggression and will run off others either by chasing them out or physically beating them. In either case stress or fight both will lead to death on smaller less stable fish.

Wow! When you say the whole family will kill each other, you mean chromis will fight clown fish too? Or those fish will kill off their own kind? I was hoping to add a percula clown to the chromis. The dt is a 200 gallon tank.

Dr. Reef · Jun 27, 2018

Firat most they will kill each other. Each cousin species will make their own territories and fend off their own first. Once non left and if that territory has other cousin species aggression will turn to them.
In a 200 gal i would guess 1 pair of clowns and 1 pair of chromis and 1 pair of damsels might be able to coexist. Guess only.