Goldfish gasping at top of tank

[linsbins7]

I currently have a goldfish in a 10 gallon tank (I unfortunately don't have room for anything larger at this time). I have had him for about six months, after my friend moved and left me with him in a 2.5 gallon tank (I quickly realized this was nowhere near enough room for a goldfish!) Ever since I've had him, he's kept towards the top of the tank, opening his mouth, which worries me. The pH level is about 7.4, I do weekly water changes of 25-30%, and ammonia/nitrate/nitrite levels are not an issue. I read that the filter creates enough surface movement in the water to create plenty of oxygen for the tank. Is this true? The tank is wider than it is taller, so it has a large surface area. Does anybody have any other ideas about what could be causing him to gasp at the top of the tank almost constantly?

 

[tarpon]

When you say they are not an issue, are they at 0?
Have you swapped out the filter media recently?
If it is just one goldfish in a 10 gallon the filter should oxygenate it enough. Is it rippling the surface of the water and creating agitation?

 

[jlk]

Your exact numbers for ammonia, nitrite, & nitrate will help! What type of goldfish is it? What do you feed him? I would start by increasing your water changes to atleast 50% atleast 2x a week, assuming your water parameters are not an issue and are not responsible for gasping at the surface.

Does he open his mouth alot like he is yawning? Heavy or rapid breathing?

 

[Laser]

I would run an airstone in there as well as increase the water changes to at least 50% and 2 times a week as JLK suggested.