Goldfish floating at bottom of tank

Question
I have a question about one of my goldfish. I believe him/her to be a fantail but I am not sure. It is in a 10 gallon tank with four other fish a small comet, a black moor, another fantail and a koi and three snails. The tank is three weeks old. For the past couple of days it has been sitting at the bottom of the tank. It will move around if bothered by another fish or one of the snail but will go right back to the bottom he will also move around at feeding time but then it is right back to the bottom it goes. As far as I know the water and temperature are both fine, I have tested them both and none of the other fish seems to be having any problems, so if you have any ideas or answers I would really appreciate your time. Thanks for your time.
LPowell  

Answer
Chris has been unable to answer your question due to computer failure. You can ask another volunteer expert or post your question on the forum at our sister site About.com in the freshwater aquarium section. There are many knowledgable members there that should be able to help. The website address for the forum is;

http://freshaquarium.about.com/mpboards.htm

Thank You for your patience. Chris should be available again in 2 weeks.