Could be a bladder infection, bladder stones or kidney stones. Could also be prostate problems if he's a male. A vet visit is needed to check the urine an place him on the appropriate antibiotic to clear it up.
Good Luck!
Edited by ZooCVT on October 22 2004 at 6:15 PM
Let me know if you have any other questions
Good Luck &
Best Fishes