two unrelated events?

[deli_conker]

I have to start with a little history on this...

Originally I had 2 Psuedotropheus Socolofi in my tank as well as what's in my signature. They got all crazy territorial and took over about two thirds of the tank. They went back to the fish store.

My two Johannis were the same size when I first got them. After several months, one was much larger than the other. The same was happening to my Yellow Labs but to a smaller degree. My Red Zebra is the biggest freakin' pig I've ever seen. I rarely saw my Ahli eat and he seemed to be growing very slowly.

The smaller of the two Johannis was definitely one of the less dominate in the tank.

I had a small stint of velvet (I'm guessing) that I treated immediately and successfully.

Within the past week or two, my Ahli's appetite has increased a bit. Within the past day or few days he's grown at a noticable pace (nothing out of proportion though) and is as aggresive or more so than the others at feeding time. He's also eating a lot and is not nearly as picky as he once seemed to be.

This morning during feeding I was doing a head count and the smaller of the Johannis didn't show up. Come to think of it, I didn't see him last night either. I also didn't see the larger of my two Yellow Labs.

I then inspected my tank and found the Johanni dead in the corner near the filter uptake. The Yellow Lab I found chillin' inside of a piece of terrain that he would normally get beat down just for swimming near it.

I removed the dead fish, and fed the remaining. I was on my way out the door for work so I haven't had a chance to check the water parameter yet (I did the full range last 4 days ago with 0 ammonia, 0 nitrItes, <5 nitrAtes, Ph 7.8, general hardness (gh?) at 16).

I'm not sure what killed the Johanni. Probably will only be able to speculate as the other fish appear healthy in all ways. At this point I can only assume it was stress related (he was not well liked(but neither was Ahli)). His death could have been any time in the last 48 hours. This correlates to about the time Ahli went food crazy.

Are these two events related?

 

[Menagerie]

I will try to help. As these fish mature, their aggression will come out more and more. Of your fish, I own two zebras (both males, but one is just now maturing), a female socolofi and used to have a female electric yellow.
My male zebra is definitely the dominant of my tank (I will admit to not having all Mbuna in the tank--fault of buying "assorted" cichlids). We have lost several smaller fish in that tank--those fish did not mature as quickly, or were just not right for the tank.

My guess is the two events were related. If you were up here in Calgary, I would send you over to a cichlid specialty LFS to get the best advice. Since you are not here, I will pass on what I learned there. Overstocking the tank will limit the aggression because there will simply not be enough to fight over. Of course, make sure your filter is up to the task and do some additional research.
HTH