Ray-Finned Fishes (Class Actinopterygii)

This group encompasses over 20,000 species of fish

Giant Grouper Giant Grouper (Epinephelus lanceolatus)
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The group of ray-finned fishes (Class Actinopterygii) encompasses over 20,000 species of fish that have 'rays,' or spines, in their fins. This separates them from the lobe-finned fishes (Class Sarcopterygii, e.g., the lungfish and coelacanth), which have fleshy fins. Ray-finned fishes make up about half of all known vertebrate species.

This group of fish is very diverse, so species come in a wide variety of shapes, sizes, and colors. The ray-finned fishes include some of the most well-known fish, including tuna, cod, lionfish, and even seahorses.



Ray-finned fishes have a wide variety of feeding strategies. One interesting technique is that of the anglerfish, which entice their prey toward them using a movable (sometimes light-emitting) spine that is above the fish's eyes. Some fish, such as the bluefin tuna, are excellent predators, speedily capturing their prey as they swim through the water.

Habitat and Distribution

Ray-finned fishes live in a wide variety of habitats, including the deep sea, tropical reefs, polar regions, lakes, rivers, ponds and desert springs.


Ray-finned fishes may lay eggs or bear live young, depending on the species. African cichlids actually keep their eggs and protect the young in their mouth. Some, like seahorses, have elaborate courtship rituals.

Conservation and Human Uses

Ray-finned fishes have long been sought for human consumption, with some species considered overfished. In addition to commercial fishing, many species are recreationally fished. They are also used in aquariums. Threats to ray-finned fishes include overexploitation, habitat destruction, and pollution.

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Kennedy, Jennifer. "Ray-Finned Fishes (Class Actinopterygii)." ThoughtCo, Apr. 5, 2023, thoughtco.com/ray-finned-fishes-2291585. Kennedy, Jennifer. (2023, April 5). Ray-Finned Fishes (Class Actinopterygii). Retrieved from https://www.thoughtco.com/ray-finned-fishes-2291585 Kennedy, Jennifer. "Ray-Finned Fishes (Class Actinopterygii)." ThoughtCo. https://www.thoughtco.com/ray-finned-fishes-2291585 (accessed June 1, 2023).