Help Please Goldfish Not Lookin Good!

[~Erik3.8.07~]

I have a common goldfish and im not sure whats wrong with him. He stays at the surface and seems to be trying to get oxygen. He stays right in front of the filter and consistantly pokes his head out of the water. He also doesnt seem to be eating the same way he used too. Like he eats alot less if any. There is plenty of oxygen in the water from the filter and the aqua clear power head thing. The water temperature isnt too warm or anything and i change about 50-75% of the water once a week. I only feed em once a day so overfeeding isnt a problem either. Can someone please tell me what may be wrong or what i could do to help! I realy dont want steve-o to die he my favorite goldfish and my first :help: :help: :help:

edit
also he is in a 10 gallon tank with a fantail goldfish and a little scavenger catfish

[Drumachine09]

What are your parameters including temperature and tank size?

[~Erik3.8.07~]

its a 10 gallon tank, the water temp is exactly 70.1 degrees the ph level is about 7.5 anything else u need to know?

[Drumachine09]

First of all, your tank is too small. Second of all, i will need nitrIte, nitrAte, and ammonia readings.

[~Erik3.8.07~]

well i dont have a test kit for that quite yet :(

[Drumachine09]

well, youre going to need one.

[~Erik3.8.07~]

just read on another thread that a fish can get lockjaw and have touble eating. My fish mouth does hang open all the time could this be the problem?

[cocoa_pleco]

i think hes just oxygen starved from over crowding. Most often large cichlids and tetras get lock-jaw, and lock jaw is rare. Out of my 10 years of having fish, only 3 tetras and 1 oscar got it

[~Erik3.8.07~]

the air pump should give him enough oxygen shouldnt it and theres only one other fish in there would take up the same amount of oxygen, but idk i guess when i get a little more money i'll upgrade the tank to the biggest size i can afford