Goldfish not eating? (alkalinity, food, small, aquarium)

[rgomez912]

Out of my two goldfish the smaller one about 4in has stopped eating. All day it looks like its sleeping since it just sits still but moves like a normal fish would when I try to get it with my net. My bigger goldfish that is 6in is fine and eating like a pig when I put food in the tank while the other just floats past the food with no interest.

My tank is 75G, readings are:
Ammonia: 0.5/6.0
Nitrate: 80/200
Nitrite: .5/10.0
Hardness: 150/300
Chlorine: 0/6.0
Alkalinity: 120/300
pH: 7.6

[Uplander]

OK, I don't do water tests so I can't help with the numbers. I did however start keeping fish when John Kennedy was president. Change 1/3 the water today, change 1/3 in two or three days and don't feed the tank for a week.

[foxywench]

you also might want to add some aquarium salt...