All fishes have fins. Various bony fish families show various degrees of fin fusion and reduction. Fins help stabilize or propel the fish in the water. Except in the lungfishes and the coelacanth, fins lack bones. In Actinopterygians, fins are supported by structures called rays.
Some bony fishes have soft, flexible fin rays.
Other bony fishes have spiny, rigid fin rays at the leading edges of the dorsal, anal, and pelvic fins. Both soft and spiny fin rays are modified scales. The spiny fin rays of some species are associated with venom glands. Glands in the dorsal, anal, and pelvic spines produce a venom that is intensely painful and is occasionally fatal to humans. There are several records of human deaths due to stonefish stings.