They are fish-shaped, 5 to 8 inches in length, and are made of pink or white marshmallow covered in a thin layer of milk chocolate with the ripples or (scales) on the fish created simply by the fish moving under a blower; this slides the unset chocolate back, creating the illusion of scales on the fish. Several companies make the fish, but the most well recognised is Cadbury. Smaller, or 'fun-sized' variants of the chocolate fish are colloquially referred to as "sprats". For a short period, in the late 1990s - early 2000, there was a Tip Top brand chocolate fish ice-cream.
In Kiwi culture the chocolate fish is a common reward for a small job done well ("Give that kid a chocolate fish").