Heat about 1 inch of oil in a large, heavy skillet to 350°F.
Combine salmon, egg, onion, biscuit mixture, cheese, and seasonings in a medium bowl; set aside.
In a small bowl, mix reserved salmon liquid and baking powder. Stir into salmon mixture. (Don't over-mix)
Shape into balls. Place crumb coating in a shallow pan or zip-lock bag. Roll balls in crumb coating, flatten slightly.
Carefully lower croquettes into hot oil. Fry in batches for 3 - 5 minutes on each side or until golden brown.
Drain patties on paper towels. Serve with tartar sauce, mustard/ketchup and/or hot sauce, if desired.
