Twenty-seven, including:
Amphiprion allardi - Allard's Clownfish
Amphiprion melanopus - Cinnamon Clownfish
Amphiprion clarkii - Clark's Anemonefish
Amphiprion ocellaris - Ocellaris Clownfish
Amphiprion percula - Percula Clownfish
Amphiprion perideraion - Pink Skunk Clownfish
Amphiprion polymnus - Saddleback Clownfish
Amphiprion sebae - Sebae Clownfish
Amphiprion tricinctus - Three-Band Anemonefish
Amphiprion ephippium - Tomato Clownfish
Amphiprion frenatus - Fire Clownfish
Amphiprion chrysopterus - Orange-fin Anemonefish
Amphiprion akallopisos - Skunk Clownfish
Amphiprion nigripes - Black-footed Clownfish
Amphiprion sandaracinos - Orange Skunk Clownfish
Amphiprion rubacinctus - Australian Clownfish
Premnas biaculeatus - Maroon Clownfish The Clownfish, or Anemonefish, are a subfamily of the family Pomacentridae. There are currently 27 species, of which one is in the genus Premnas and the rest are in the genus Amphiprion. The other pomacentrids are called damselfish.

Clownfish are native to wide ranges of the warm waters of the Pacific; some species ranges overlap others. Clownfish are not found in the Atlantic. Clownfish live in a mutual relationship with sea anemones. Once an anemone has been adopted, the clownfish will defend it vigorously. However, clownfish in an aquarium environment can exist very well without an anemone. (This may be advisable as anemones are extremely difficult to keep alive even for experienced aquarists.) To avoid the stings of their host anemones clown fish have secretory cells producing a layer of mucus on their bodies. The mucus is based on sugar rather than proteins so anemones fail to recognize the fish as food and do not fire their nematocysts, or sting cells.

Clownfish are among the few marine fish that can be bred in captivity in commercially-viable quantities at the time of this writing. Hobbyists are advised to purchase captive-born clownfish (and other marine animals) whenever possible. The Amphiprions are attractive in colour and usually wear bright colours. Example: orange, black, and white. They are good for a marine aquarium because they are friendly and easy to feed. They adapt well in captivity and can be easily studied for scientific research. These warm water fish have a higher metabolism which makes them more active than the cold-water fish.

Clownfish lay eggs on any flat surface close to or under protection of their host anemones. These eggs are cared for by the male and hatched under complete darkness after a period of 7 to 10 days. Hatching occurs in a natural rhythm directly connected to the phases of the moon. Clownfish are omnivorous, their diets range from flakes to meat. They feed mostly on copepods and mysids, the undigested excrement from their host anemones.

Clownfish are relatively small organisms, fish in aquaria can grow to 9 cm (3.5 inches) in length, fish in the wild can grow to a length of 12 cm (5 inches).

Reproduction

Clownfish are protandrous hermaphrodites, meaning they are hatched as sexually immature fry. Based on signals from their environment and being physically mature (12-24 months) they will either remain sexually immature, change into a male or change into a male then female. A group of clownfish is always built into a hierarchy of this type, with the female (the largest and most aggressive) at the top. The change from juvenile to male, and male to female is irreversible. If the female should die or be removed from the group, the most dominant male then changes into a female, and the rest of the males move up a rank on the hierarchy.

In typical home aquaria, a juvenile only several months old can make the change from juvenile to male to female in as little as a month. Because of this, pairing clownfish can be a tricky proposition, as most hobbyists tend to select the largest and most dominant specimen (presumably a female) to mate with their own female. Usually two females will tend to fight regularly, and frequently lock jaws (some hobbyists describe it as kissing). In a successful pair, the male will exhibit submissive behavior. Usually, this behavior entails the more aggressive female darting at the male, and the male turning sideways and quivering.

Most common species of clownfish (A. ocellaris, A. percula etc.) are fairly easy to breed in the home aquarium. The female will be the largest of the pair, and the two fish will usually stay close to each other in one area of the tank or in a host anemone. After several months in a successful pair, the fish will begin spawning. The female's abdomen will bulge with eggs, ready to be deposited. She will usually find a flat surface near her host anemone (if present) to lay her eggs before they can be fertilized by the male. The eggs will normally hatch in 6-11 days depending on temperature and other water parameters. In home aquaria, the fry must be reared in a separate aquarium on a diet of rotifers then baby brine shrimp to have any chance of survival.

References in media

Clownfish featured prominently in the 2003 Pixar-animated movie Finding Nemo. Despite the content of the movie - wherein a young clownfish's father must rescue his son after being stolen to be sold as a pet - public demand for clownfish as pets has tripled shortly after its release. Some environmental protection activists regard this as a catastrophe as the species is already facing the threat of extinction due to a reduction of its natural habitat (coral reefs) which in turn is due to global climate changes as well as pollution of the seas.

It is also feared that people may have attempted to send fish back into the open sea by flushing them down the toilet as demonstrated in the film; unfortunately, they will not be able to survive the canalisation or the sewage plant. Another problem is that many buyers lack basic knowledge -- like needing a saltwater tank -- to take care of such speciality fish.