try holding it up to a light to see if you can tell whether or not there are stones in there. If it is gravel, my bet would be that it's several small pieces rather than one large oval stone.
Maybe a tumor?
have you tried the epsom salt yet? even if it's not gravel, and some other type of blockage, you're not ready for last resorts until 1) you've tried the laxative, and 2) the fish is being negatively affected by the blockage/growth?.
Maybe a tumor?
have you tried the epsom salt yet? even if it's not gravel, and some other type of blockage, you're not ready for last resorts until 1) you've tried the laxative, and 2) the fish is being negatively affected by the blockage/growth?.