Bite marks?

[jaimoe]

I have a cobalt blue zebra who has always enjoyed a pretty comfortable status in my 75 gallon mbuna tank. He's one of the originals, and has over the past few months grown into one of the larger fish in the tank. Suddenly, he seems to be getting the stuffing beat out of him, though. It's kind of straight out of nowhere, but he's being brutalized by my afra and my red zebra, and who knows who else. He hides in a corner under a plant for the most part nowadays, when he used to be out in the open most of the time. Here's a pic of him with what I think is a bite mark.

I talked to my girlfriend recently and she says he now has more of these markings on his head. Anyone know what might cause a previously well stationed fish in tank society to be so quickly demoted to tank punching bag? I have a strict weekly water changing regimine, about 20-20% a week, and keep the PH in the low 8's, temp in the high 70's.

 

[semper fi]

maturation. fish that seem to get along well may not as they sexually mature. they establish territories and one is usually king of the tank. might have to move him to make him less stressed.

 

[jaimoe]

Thanks, semper fi. That sounds plausible. The fish in my tank average about 4" now where they were about 2 1/2 inches on average when I first stocked the tank back in March. Unfortunately I have nowhere to put him because the juvie tank I have is filled with young cichlids of less than 2", more like 1 1/2 inches. I have alot of caves but some of my larger fish are taking two and three of them for their territory. I don't know why I always assumed each fish would take one cave for his/her own and leave the rest to the others. Oh well I've been meaning to re-arrange things in that tank anyway, and stack the caves a bit higher. I guess this is a good excuse!

Thanks again!

jaimoe