Clown fish

You may know of the Clownfish from the animated film Finding Nemo. They are a common sight in the oceans around Thailand, if you know the right places to look and their characteristic features to look out for. Clownfish (members of the Pomacentridae family) are special little fish that even the most experienced diver can’t resist taking a swim with them.

Distinguishing features

An unmistakable sight around reefs, Clown fish are bright orange, with three vertical white stripes around their bodies, and fringes of black outlining their fins. These fish are extremely fast, constantly darting in and out of the anemones tentacles.

Clown fish come in many different sizes, the largest reaching lengths of 13 cm, whilst the smallest can barely grow to 5cm.

Habitat

They prefer warmer tropical waters and predominantly live in sheltered reefs, most famously the Great Barrier Reef, or in shallow lagoons. More specifically, Clown fish have formed symbiotic mutual-isms with sea anemones. Although sea anemones are lethal to other fish, the Clown fish has evolved a mucous membrane on its body to protect itself.

Clown fish and sea anemones provide many benefits to each other. Fecal matter excreted by the Clown fish provides essential nutrients to the sea anemone. In return, the anemone protects the Clown fish from predators, whilst simultaneously providing a constant supply of food.

Feeding habits

Clown fish, like most Anemonefish are omnivorous. They mostly eat small zooplankton, such as copepods and tunicate larvae. However, they also eat algae and feed on undigested food from their host anemones, as well as dead anemone tentacles.

Reproduction

Like many other sea creatures, Clownfish are sequential hermaphrodites: they are born males and, once they mature, a select few with then become females. One mating pair in a group of anemonefish at a time.

As well as homes, the anemones also act as nest sites. The female Clown fish lays eggs on a flat surface close to her anemone host. They usually do this around the time of the full moon and their reproductive cycle closely follows the lunar cycle as the fish can sense the strength of the current.

The male guards the eggs until they hatch 6-10 days later.

Life cycle

There is a strict hierarchy established in a group of Clown fish. The dominant female, usually the most aggressive and largest, will mate with the largest male and form a colony. Clownfish tend to live in small groups, including the mating pair and a number of juveniles.

They can live up to 10 years in the wild, but most only live, on average, 6-8 years.

Clown fish facts

• An extremely common sight in salt-water aquariums, this fish is one of the most popular on the market, so much so that some governments have put restrictions on how many can be removed from the wild.
• The Clownfish is also known as the anemonefish.
• They are fiercely territorial and will defend their host anemone from others.
• Although they are not endangered, the Clownfish are at risk due to destruction of reefs, pollution and trawler fishing.
• Clownfish are called Pla Cartoon (ปลาการ์ตูน) in Thai.