WCMM Harassing My Other Fish

[michael]

I have a 40g with 12 Bloodfin Tetras and 11 WCMM. My WCMM are bothering my bloodfins by nipping them and chasing them constantly. My bloodfins don't come out much because of this.

I have removed all the WCMM and put them into a container temp by themselves. I need advice what to do with them now.

My Bloodfins seem much calmer and happier without these WCMM in the tank.

I did research on the WCMM and it says they only harass their own kind but that is not what I see in the tank.

[exv152]

In my experience when shoaling fish, that are otherwise peaceful, begin nipping or showing aggression it's most likely because the environment they are in is maybe stressing them. Is the shoal too small, the open swimming space too crowded, or the termperature is too warm? Could be that they're not used to the new company. Maybe try reducing the bloodfin shoal to the same number or less, and then gradually increase.

[michael]

The shoal is 11 WCMM and 12 Bloodfins. I checked the temp with 13 thermometers and the temp reads 74½ to 76 between the thermometers.

Now I only have Bloodfins in the tank. I put all the minnows in a glass container temporary.

http://youtu.be/bwSj0PEp9Uo

[bergenm]

I would say two possible reasons for this:

They are both top strata fish - ie they both generally live in the top 1/3 of the tank so they are competing for the same real estate.

White clouds can get pretty nippy when breeding, they will nip at each other and anything else in the vicinity.

You can keep them together and the bloodfins will probably get used to living lower down in the tank, or get rid of one of the schools and replace them with fish that live in a different strata...

or get another tank... 

[michael]

Thanks for the advice. I did separate them. The WCMM have their own tank now. My Bloodfins like their own space.