55gal cichlid tank

Question
Hey Chris -
I have a 55gal cichlid tank that I had 11 cichlids in.  I haven't lost any fish in that tank in over 6 months.  I do regular water changes and my fish have been healthy and seemed to be thriving. Up until two days ago that is.  I removed a large tree decoration from the tank the other day and replaced it with two small decorations.  The large decoration I removed was there favorite hiding spot.  About an hour after I did that we noticed a few of our fish looked listless.  Since then I have lost 3 cichlids and two catfish. I just did a partial water change and a roc vac last week.  This morning I walked into my living room and it smelled like boiled eggs.  The tank smells like boiled eggs, or rotten eggs.  We tested the water and the ammonia was through the roof so we treated that. I read your answer about the waste and bad bacteria being disturbed and killing the fish.  Does that sound like my problem?  I am thinking maybe removing that big decoration that had been in there for a good 6 months disturbed some toxic waste and that is what is my problem...does that sound right?  If so what do I need to do...a partial water change or a complete water changed removing and cleaning the rocks?  Thanks so much for your insight! Diane  

Answer
Hi Diane;

I think you're probably right. The covered up gravel became a toxic area and once it was exposed, the organic waste that was trapped in there began to rot so ammonia went up. I would vacuum the gravel several days in a row in those spots to remove as much of that ugliness as you can. Siphon out 25% of the water every day as you vaccum. You don't want to remove too much water at one time or it will shock the fish. Hopefully that will do the trick. If you really think the fish aren't doing any better in a day or two, you could remove 50% of the water in one shot. I hesitate to recommend it though. It can be pretty hard on them. Just always use a good water conditioner and be sure that the new water is the same temperature as what's already in the tank. I hope it gets better and all goes well. ..

At Your Service;
Chris Robbins