my fantail goldfish seems to be acting wierd

Question
QUESTION: i have two fantail goldfish in my tank and one floats on the very bottom swimming a little and when the other nudges it and it goes to the top swims for a bit then floats back down and the other not leaving its side and it also swims to the top for food, but it also swims in 1 spot, is this normal?

ANSWER: Michael,

 Goldfish are one of the most difficult fish to keep. Since they do not have a stomach, they produce a lot of waste. It is never normal for a fish to not swim. Does it look bloated at all? What are you feed it? What are your water readings? DO we know the sex of the fish? Is it having problems staying upright? Give me as much information as you can since I am not there and cannot see the fish. As soon as you get back to me I can help you out better.

---------- FOLLOW-UP ----------

QUESTION: ok, he doesnt seem to be bloated, i dont know what the water content is, but i am feeding him/her fish flakes for fantail, and i do not know if it is a male or female, how do i determine the sex of the fish?

ANSWER: Michael,

I would suggest that you get a water testing kit if you want to keep fish. With what you are describing there might be a water problem. There should me no ammonia or nitrites in the water ever. Sexing fish is not an easy thing to do especially if they are young but here is a website that might help.

http://www.kokosgoldfish.invisionzone.com/forum/index.php?/topic/38013-male-or-f

---------- FOLLOW-UP ----------

QUESTION: well i found out that it is a femal, and ammonia and nitrate levels are 0, but she still floats and stays in one spot,

Answer
Michael,

She might be suffering from swim bladder disease. I would do the fasting and feeding of the cooked shelled pea and then fast again and see if that helps her at all. Make sure when testing the water you are not using test strips. They are not accurate. The liquid testing kits are the best. Let me know how things go after you feed her the pea.