Help - My Cichlids Keep Dying Unexpectedly

[neilpet]

Greetings, fellow aquarists...

I have a problem that is becoming distressing, so I'm asking for any advice I can get. I have a 100 gallon tank with the following inmates:

4 green sevrum (2 large, 2 smaller)
1 male electric yellow (females keep dying unexpectedly)
2 medium parrotfish
1 gold tinfoil barb (6 inches)
2 tinfoil barbs (6 inches)
3 giant danio (3 inches)
2 small plecos
3 bleeding heart tetras
2 blue peacocks (1M 1F)
1 Geophagus brasiliensis
2 strawberry peacocks
2 unknown species (pair, 1 orange female 1 blue male) second female died this morning
1 small OB peacock

The filter is an Eheim cannister. There are two in-tank heaters. I do a 15 gallon water change at least once a week.

The tank is currently divided 2/3 1/3 to keep the largest sevrum from killing the second largest one. He ignores the two smaller ones.

Problems are: I can't keep the smaller cichlids (peacocks, electric yellow females, etc.) alive. They show no indications of poor health, then I find a corpse in the morning. I'm losing about 2 fish a week. I THINK this problem is related to a pH issue. Our tap water here in Calgary, Alberta, Canada is coming out at about 7.5, and my tank keeps plunging to 6 or lower. So I do a 25 gallon change to bring it up again and then it drops. Nitrites show at zero, as does Ammonia. My wife's 100 gal tank has no such issues.

The male electric yellow seems to be fine. It's the females that die. I've lost recently one of my OB peacocks, two female electrics, one strawberry peacock, and one of the unknown females. All these fish have been at least 2 inches in size.

I'm wondering if they are being stressed by the Tinfoils activity. They seem to get very agitated when the lights go off at night.

Any advice will be welcomed.

I hope this isn't the wrong place to post this. I looked elsewhwere, but couldn't find a 'help' forum.

Neil

 

[rdp50734]

Have you got anything in your tank that could be lowering your PH? Bogwood stones ornaments etc..?

 

[Big_eyes]

Seems like a lot of fish you have in there for a start.

What do you have in the way of decor/caves etc for territories?

The drop in ph probably wont do much good but as for whats causing that I can't really help.

 

[OldMan47]

Welcome to the forum Neilpet.
If your water is fairly soft, it will have the pH move about easily. Fish waste becomes nitrates once it has been processed through from ammonia. A common form that the nitrates take is nitric acid which will of course drop the pH. The heavy fish load that you have in that tank means you are producing more acid concentration than in most well maintained tanks. The only real option for soft water type fish is frequent large water changes to hold down the nitrate levels.
If you stop replacing the fish that you lose, you will eventually get a light enough fish loading for your present maintenance practices. Another option, that I would prefer to see, is to do more frequent and larger water changes. If it was merely a pH problem, and not a bioload problem, you could halt the pH drop by simply adding some crushed shell or crushed coral to the filter flow path. People take some of the carbon out of the typical media bag and fill the space with shell instead. By slowly dissolving the shell, the pH and hardness are both raised. That will not deal with the nitrate production rate but would help keep the pH from falling.

 

[chrisbassist]

Ooh, thanks oldman47. I did wonder why discus keeping required more water changes, that explains it.

 

[kaivalagi]

Ooh, thanks oldman47. I did wonder why discus keeping required more water changes, that explains it.

I thought that was just a general sensitivity to Nitrates and the after affects that required more water changes for Discus, if they are in a low pH but hard water then the pH won't shift like above but you would still do more frequent water changes right?