[DJRansome]

Too ambitious IMO. I would do hongi and maingano in a 48x18 tank or larger.

Cynotilapia zebroides Cobue have a similar look to hongi, and you could do the yellow labs with them.

 

[DJRansome]

I would not go 3 species...this is a 42" tank as you say. The Hara is larger and more aggressive than the zebroides Cynotilapia.

Labs and rusties would work too.

 

[DJRansome]

Yes rusties and cobue could work. You remove extra males as they mature if they cause trouble. I would expect the rusties and cobue to color best with one male of each in the tank.

 

[DJRansome]

I would cycle the tank without fish and with ammonia. It is not expected for rusties to kill each other 4 hours after adding them to the tank, but you should not have any nitrites either.

What pH are they at at the LFS? I have seen fish in pH shock, but never seen one die of it.

 

[DJRansome]

No it is common that one fish shows the stress and the rest seem fine initially.

Aggression deaths usually take longer, it is a long slow harassment over many days with the fish lurking under the surface or behind filter intakes or heaters.

A death in 4 hours from aggression would be like a blunt force trauma from being rammed which can happen but I have never seen.

Did you observe relentless chasing on the part of one of the fish?

 

[DJRansome]

Which one is chasing the most? Maybe he needs to go?