Help, fish may be dieing!

Question
I have a Texas Green Cichlid, which I believe to be about 2 years old, he is 10 inches long, about 2 or so thick, and maybe 5 or 6 tall.  He lives in a 55 gallon tank with 2 emperor 400 filters which i wash out bi-weekly.  I have a heater which is kept at 80, but I have 2 thermometers that read about 78 or so, and do water changes(6-9 gallons bi-weekly)  I have given him hiding places, as well as swimming room, He normally eats a lot, but hasn't been eating lately.  He has what I think was something called Velvet disease, which I changed prob 12 gallons of water, added a little bit of a general disease preventer and got Mardel, Maracide to treat it. I put the recommended dosage in and have added a little aquarium salt to help his immune system.  Although if he is not in his 'house' he is literally sitting/laying on the bottom of the tank, directly on the rocks, right next to the heater.  If I approach the tank he will awaken and come to me or retreat to his "house".  Can you please give me advice as to anything to try to help him. I love him and have tried all I can think of to help him, but its 12:45am and I am going to go to sleep soon and fear during the night he may lay on the bottom all night and die.  A lot of the white stuff has come off of him and he has been looking better but his laying on the bottom has never occurred with him before.
P.S. I checked the
PH= 7.5
Nitrate= barely on the chart
Nitrite= barely on the chart
Ammonia=Barely on the chart
He moves rocks around and inter acts with me but if i go sit and watch TV he sits near the heater laying on the bottom, I'm worried. please help me out. Can you please e-mail me directly(wdjlaudio11@aol.com), and i will check as much as i can, and will return to this website, but i am unsure of how to locate what i posted on here.

Answer
Hi Jamie,
 It sounds like he has ick. Ick looks like a fine dusting of icing sugar on the fish and is particularly visible on the fins.  If that is it, then you need to use a product like Rid-Ich or Quik-Cure specifically designed to kill ick.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>