African Cichlid

Question
Hi Karen,
I have a 75 gallon tank and had a pair of "yellow lab" cichlids that mated twice for me. I kept one of the babies and gave the rest away.  I then got an Electric Blue Maingano and as he matured became very aggressive. I ended up finding another home for him but my male lab was very stressed, turned black and I lost him. Shortly after, I also lost my female. I was very disappointed since I've had these two for about 5 years. I got two more small yellow labs but now the "baby" from the first pair (which is full size now and is about 2yrs old) is starting to turn black.  I do not think this one is stressed. Is there something else that could be going on with the tank. My water tests fine so I am at a loss of what may be causing it. I could really use your help as I don't want to loose that one too.
Thank you so much for your help.


Answer
Hi Pat,
I'm sorry to hear of your loss.

Its difficult to pinpoint right away. Fish turning black like that usually indicates the fish are uncomfortable with their environment and/or stressed. Have you absolutely made sure the ammonia and nitrite levels are both ZERO and nitrates are under 20? And that there are sufficient hiding places for the fish to feel comfortable?

I would start trying to solve this mystery by doing a 30-50% water change on the tank to help relieve some stress and remove excessive pollutants that are more than likely present.

See how that works for a while. Make sure the filters aren't clogged, the gravel isn't clogged in spots producing dangerous pollutants from decomposing waste.

I do hope all goes well and best of luck!
Karen~