If thats it you have a big problem. Dry wall is messy, and can be dangerous if its growing mold. All you have to do is push on it. If you push it in, you have a problem.El Barto said:do you smell it strong when you smell the suface or is it near the aquarium? ive had problems in the past of getting mold or something on the walls near the aquarium and behing the tank. it really smelled freaky.