[sir_keith]

I agree with the comments above- this is likely a stressed fish that is being harassed. Your only course of action is to isolate the fish and let him recover, however you are able to do that. A breeder box is not a long-term solution.

What you're seeing here is one reason that it is difficult to keep just one Tropheus tank- you have no place to put individual fishes when they get harassed, something which in the long-term is inevitable. Good luck.

 

[sir_keith]

Thanks. Sadly he died overnight...
The lesson from this is probably to get en extra tank, as a recovery one. Thanks for all help

Anyone who has ever kept Tropheus for any period of time has suffered a loss like this; it comes with the territory. That said, just getting an extra 'recovery tank' may not solve the problem, for example, see the recent thread on 'Time Out' in the Malawi section (Does cichlid time out work?). I have several Tropheus species tanks in my fish room, and when one individual is being harassed, I move him into another tank that is devoid of conspecifics. For example, I recently had to move one of my T. sp. 'Red' Lunangwa South individuals into a tank with less aggressive fishes (T. moorii Mpulungu) to recover, and after a few months, I will move him back into the original tank. This has worked for me on several occasions in the past, but only after a long hiatus. A more typical solution is to re-home harassed individuals as the colony matures.