Diagnosis Help - Desperate!

[juhoo26]

I have had a Cichlid tank for several years now and everything has always been great. I do weekly water changes and have a good filtration system. However recenly I have noticed that several of my fish have been getting really skinny, they are eating good but seem to be losing weight. These same fish also have greyish colored patches on their scales, or there color changes to a darker version or their original, it looks almost as if the scales have been scratched up. They also seem lethargic and somtimes can be seen just setting at the bottom, gasping for oxygen. They seem to live this way for several months and then one day they will just die. I have been searching for any information on this problem but I haven't been able to come up with anything can anyone here help me?

[Dan Woodland]

Sounds like old age (depending on what several years means) or possibly an internal parasite. Try feeding a medicated food or treat with clout (this is strong and may be too hard on weak fish so try a weaker does to start). Good luck.

[juhoo26]

I should have been more clear, I have had the tank operating for two years.