Lake Malawi Species • Cobalt blue aggression

[ironspider]

I have two adult Cobalt blue males and two females, the males are so beautiful I can't fathom re-homing them. They've been in the same established tank since juvenile for 3 years now and while they've always been aggressive, it's gotten out of control. I think said aggression led to the death of one of my female yellow labs, but they are always chasing someone around the tank. It has gone from a quick chase to an extended chase in some instances, through the rocks and such.

5 cobalt blue (2 female, 2 male, the fifth is young so I have no clue)
2 yellow labs male
2 yellow tail acai one male one female
1 demasoni sex unknown, i'd guess female.
5 rusties, not sure of sex.
1 ob, sex unknown.
1 BN pleco

All water parameters are good. This is a well filtrated 4ft 55gal with a lot of rockwork and hiding spaces.

I was thinking of removing all the rockwork, rearranging it and changing the tank temp from 81 down to 79.

Please chime in with suggestions. I cannot re-home these guys though.

[DJRansome]

Temp of 78 is a given so you can try that, but I would not expect it to have an impact.

I would not remove rockwork as the fish are rock fish. If anything I would add rockwork.

Rearranging can have the opposite effect, so keep that in mind.

You won't rehome the callainos, but what about some others? You could add a bunch of callainos females, but you would have to remove an equivalent number of fish.

[ironspider]

What's a bunch? I have a few Rusties I wouldn't mind rehoming.

[DJRansome]

Ideally you would add 8 or more callainos females and remove an equal number of other fish. Still 2 male callainos in a 55G could all be for nought.