strange chromis behavior

[mdsnlwlsn]

last night i spent a good time watching some strange behavior my chromis were doing. there are 5 of them in my tank(30g) and one of them is clearly smaller and different looking than the others. one of the bigger ones kept cornering the small ones into an enclave in the live rocks, keeping it from leaving or from any of the others from coming near. it seemed to be semi-aggressive behavior. every once in a while the two fish would drift out from the enclave, but soon the same fish would look at the other one and start the process over again. the smaller one also seemed to have some wierd spots or something... my only guess is that maybe the small one is female and this is some kind of mating behavior? seems unlikely because i have a fairly new tank and i have heard they're hard to breed. any thoughts/ experiences with this?here's some pics, you can see how its cornering the smaller one and you can kinda see the wierd spots

thanks!

 

[Paul_N]

I had chromis twice. The first time I had 6 and the second time I had five. The same thing happened both times. They would harass the smallest one till it died one by one until there was one left. I gave up after that.

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[Madreef]

It is normal for them to pair up and try to pick on the smaller ones. The rule is keep one or two, some people have good luck with a group but 9/10 times that's not the case. If you want to get a group of fish for your tank you might look into some of the smaller gobies that can be kept in pairs. Your aquarium doesn't have much space for many fish unfortunately. Good luck with the remaining chromis.

 

[bct15]

I have six in my 150...they do not do that but they do spawn often. It looks similar to cichlids spawning, as they are dancing in circles on a rock. It is not difficult to get chromis to spawn it is difficult to raise the offspring. Your behavior sounds more like bullying, your tank might just be to small for that many chromis...

I've had six for about two years

 

[STL]

Unfortunately, it's probably aggression. I started with two green chromises in a 55g. LFS suggested adding a 3rd due to the combat going on. The 3rd was larger and within a few months stressed the other two to death, one by one. So now I have one very big bully of a chromis.

 

[mdsnlwlsn]

ok.. that makes sense. last time i tried 3 chromis, and all that was left was the largest one. i then got 5 more, and one of those died and was eaten by hermits the other night. this definitely seems like agression, after watching them feed the two smaller/ weaker ones weren't allowed up to the surface to get any food, and they don't look so healthy.. one is actually not swimming well and being chased by hermits... i guess i'm going to stay away from groups.

 

[Paul_N]

When I was down to my last two, the one chromis actually would try pairing with an anthias. It would always swim next to the anthias and when the other chormis tried it would turn around and chase it into a corner and then go back to swimming with the anthias.