Fish mounts tend to be more delicate than other types of taxidermy creatures. Mounted fish are coated with a liquid sealant and a glossy finish. Commercial cleaners can be too harsh for these outer coatings, and in some cases, can dissolve or damage them. Additionally, the fins on these items tend to be very delicate and can snap or crack it they aren't handled with the utmost care. Clean your mounted fish gently to ensure that it remains in good condition.
Take the mounted fish off of the wall, being careful not to bump the delicate fins against anything. Lay it on a flat surface.
Spritz a dust cloth with a small amount of dusting spray. Make sure that the spray does not contain wax; it should be a multi-purpose dusting spray that's appropriate for surfaces other than wood, such as Endust.
Wipe down the body of the mounted fish with a dust cloth. Lightly coat the end of a cotton swab with dusting spray and use it to clean the crevices around the fins and gills. Gently dust the fins with the cloth. Be careful not to catch the cloth on the tips of the fins.
Use a compressed air canister (the type designed to clean computer keyboards) to remove dust from inside the fish's mouth and gills, and from between the fish and the board it's mounted on.