Orange clownfish

Amphiprion percula can grow to be in length, but is on average , and can be recognized by three white lines across their bright orange bodies, with no distinction in color between sexes. The anterior white bar is placed just behind the eye, the middle bar goes straight down the middle of the fish, and the posterior bar occurs near the caudal fin. An anterior projecting bulge also exists on the middle bar. In addition to the white coloring, black edging outlines each fin with varying thickness. ==Reproduction==

Since these fish live in a warm-water environment, they can reproduce all year long. Each group of fish consists of a breeding pair and none to four nonbreeders. Within each group there is a size-based hierarchy: the female is largest, the breeding male is second largest, and the male non-breeders get progressively smaller as the hierarchy descends. They exhibit protandry, meaning each fish is born male, but changes to female if the sole breeding female dies. If the female dies, the breeding male becomes the breeding female, and the largest nonbreeder becomes the breeding male. The spawning process is correlated with the lunar cycle. At night time the moon maintains a higher level of alertness in A. percula and this increases the interaction with the males and females. Before spawning, the male attracts the female via courting behaviour. These courting actions include extending their fins, biting the female and chasing her. The males also swim rapidly in an upward and downward motion to attract the females. The nest site is also important for the survival of the eggs. The expected tenure of breeding females is roughly 12 years and is relatively long for a fish of its size, but is characteristic of other reef fish. Why the nonbreeders continue to associate with these groups has been unclear. Unlike nonreproductives in some animal groups, they cannot obtain occasional breeding opportunities, because their gonads are not functional. They cannot be regarded as helpers at the nest, since their presence does not increase the reproductive success of the breeders. Recent research suggests that they are simply queuing for the territory occupied by the breeders, i.e. the anemone; nonbreeders living in association with breeders have a better chance of eventually securing a territory than a nonresident. A. percula is a very competitive fish and this causes the smaller fish to have stunted growth. A potential exists for a fish to ascend in rank by contesting its dominant. This depends on the relative body sizes of the two fish, and is very unlikely to happen since A. percula maintains well-defined size differences between individuals adjacent in rank. However, in an aquarium, this fish is peaceful, and it can live in an aquarium environment well. The fish lay their eggs in a safe spot close to the anemone from where they are easily protected, and the parents can retreat to safety if danger threatens. Anemonefish usually lay their nests in the evening after a few days of carefully cleaning and examining the chosen site. Preferred egg sites are flat or slightly curved rocks or some other item the fish have dragged near their nest for the purpose. (In captivity, clay pots and saucers are an attractive choice.) First, the female deposits some eggs with her ovipositor (a whitish tube descending from her belly), making a wiggling pass over the surface, then the male follows behind her, fertilizing the eggs. After many passes, the nest is complete and will hatch in 6–8 days shortly after sunset, usually on a very dark night. In the meantime, the male is very protective of the nest and ceaselessly fans the eggs to provide proper oxygen circulation, and checks them for any bad eggs, which he eats before they can rot and damage more eggs. Females may help the male tend the nest. At hatching, the larvae burst free and swim up toward the moonlight and the open ocean to ride the currents and eat plankton for about a week, before the still tiny metamorphosed clowns return to the reef and look for an anemone in which to settle. Eventually, the cycle repeats. ==Recruitment==

Recruitment is the number of individuals in a given species that can survive within a certain amount of time following larval habitation. The higher the level of recruitment, the better chance a larva has of surviving long enough to become an adult fish. Large food supplies, low predator threats, and the availability of nearby anemones are all factors that affect their recruitment levels. A. percula, like most coral reef fish, has a bipartite lifecycle, which has a scattering pelagic larval stage, whereas its resident phase is motionless. At the end of the pelagic phase, the larvae begin to settle on the coral reef and begin their recruiting process in the resident population. Larvae that settle successfully and join a resident population are called recruits. Anemonefish species are recruited to areas where the fish are commonly found. Most anemonefish are site-attached and do not move from one anemone to another that are spatially distributed more than a few meters. This is simply because it is always a dangerous undertaking for A. percula to be outside its anemonefish safe haven, exposed to dangerous predators. They are also very poor swimmers, increasing the risk involved in travel. Recruitment is essentially the only method that the fish can use to inhabit new anemones. Finding a better living situation in a different anemone is unlikely because every anemone is already occupied by other anemonefish species. Anemonefish are known for reproducing all year round when they are in lower latitudes and recruitment with these fish is anticipated to follow the same pattern. ==Habitat==

Anemonefish are specialized coral reef fish that live within host anemones and are found in warmer waters in the Pacific and Indian Oceans, off northwest Australia, southeast Asia, and Japan. Both A. percula and the anemones reside in shallow waters and the depth usually does not exceed 12 m with water temperatures ranging between 25 and 28 °C. This could allow them to be preyed upon more easily, and lead to higher population mortality rates. Impairment of larval olfaction may also make them less able to locate appropriate reef habitats at the higher levels of ocean acidification that are projected to occur with increased carbon dioxide emissions. A paper published in Nature in 2020 cast doubt on the effect of acidification, stating "our findings indicate that the reported effects of ocean acidification on the behaviour of coral reef fishes are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO2 oceans". A meta-analysis published in 2022 also found that effect sizes of studies assessing ocean acidification effects on fish behaviour have declined dramatically over a decade of research on this topic, with effects appearing negligible since 2015, representing one of the most extreme examples of the decline effect in ecology. ==Development==

The development of A. percula is relatively fast. After the eggs are fertilized, they are ready to hatch after about 6–7 days. After hatching, the larvae are very small and are transparent except for the eyes, yolk sac, and a few colors across the body. The larvae then sink to the benthic environment, but then swim to the upper water column. The larvae spend about a week floating among plankton and are transported by ocean currents. The larval stage ends when A. percula settles to the bottom of the ocean. The process from larval stage to juvenile takes about one day. Rapid development of color occurs during A. percula's juvenile stage. During the juvenile stage the anemonefish has to find a suitable anemone host. Specific chemical components are used when finding their host. These chemical cues are different for each anemonefish. This causes preferential selection when finding their anemone host species. When A. percula comes in contact with the anemone, it produces a protective mucous coat. This mucous coat is developed with multiple interactions with the host anemone. A. percula dances around the anemone, touching its fins first to the tentacles and then its entire body during its first interaction with the anemone. This process could take a few minutes or up to several hours. If A. percula does not continue to come in contact with the host anemone, the protective mucus may disappear. A. percula belongs to a group of fishes that are not stung by the nematocysts of the anemone. If A. percula did not have the protective mucous covering, it would be stung. Other fish species that lack the mucous covering are consumed by the anemone. ==See also==