Bony fishes are ammonotelic animals.

Ammonotelic organisms are the kind of organisms that remove the waste product from their body in the form of ammonia.  They are mostly aquatic organisms.  Fishes and other organisms that have an aquatic habitat release nitrogenous waste from their body in the form of ammonia.  This is done because ammonia is highly soluble in water. The nitrogenous waste in the body of these organisms goes through the process of deamination to convert it into the final waste product.