You sure it was the temprature causing this? I never noticed any difference in behavior, or color. I personally, always keep my big Cichla on the lower side. In the case of an outtage or something so they do not stress out as much, due to the decreasing water tempratures. If I had them at something like in the high 80's.
If your going to drop the temprature, do it slowly. Dropping it from the high 80's to mid 70's can cause the lethargic and color issue, I am sure. Maybe over the course of a few water changes, you could sneak in a drop of a couple degree's.
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