Mandarin fish, marine fish with 1000 colors


The mandarin fish did not steal its scientific name of Synchiropus splendidus because its brightly colored body is a real splendour. This tropical species native to the Pacific Ocean is very popular in aquariums and can live in captivity under the guidance of experienced aquarists. Although small in size, the mandarin dragonet irradiates the seawater pools with its 1000 colors, patterns and reflections. Portrait of a natural wonder.

Who is the mandarin fish?

The mandarin fish (Synchiropus splendidus) is also called mandarin dragonet, mandarin goby or even cashmere fish. The marine animal belongs to the order Perciformes and the family Callionymidae, which brings together benthic fish divided into around twenty genera. There are nearly 200 species of callionymids, commonly called dragonets because of their strange appearance, without scales. The Latin qualifier splendidus (brilliant, dazzling, resplendent) directly alludes to the spectacular colors of the fish. As for the term Mandarin, it evokes the colorful traditional outfit of senior Chinese officials.

What are its physical characteristics?

The mandarin fish has a large triangular head enhanced by two prominent, mobile eyes. Its small, protractile mouth is equipped with several rows of tiny teeth. In this species, sexual dimorphism is particularly pronounced: the male has a more elongated snout and measures up to 8 cm long while the female is significantly smaller and has a very rounded belly. Both sexes have 2 dorsal fins but the first soft ray is almost twice as large in the male. When not erect, this growth folds down and can even reach the caudal peduncle. In mandarin fish, the gill openings are reduced to small tubular orifices.

What are the colors of mandarin fish?

Synchiropus splendidus is distinguished above all by its colorful pattern, especially in the male during the breeding season. There are a multitude of shades, intensities and designs depending on the individual but their livery has a brown-orange base with sinuous bands and bright green-blue spots, embroidered in black, on the body and dorsal fins. and anal. We also notice yellow spots. According to studies, mandarin fish have blue chromatophores called cyanophores in their integuments, which generate the blue color. Cyanophores are pigment cells that contain phycocyanin, a protein that absorbs red light and reflects blue light. This phenomenon explains why the blue color is visible on parts of the body where the skin is thinner, such as the fins.

Mandarin fish: what is special about its skin?

Instead of scales, which it lacks, the mandarin fish has thick mucus which allows it to protect itself against external attacks. Its viscous skin acts as a physical barrier against parasites and predators. This thick mucus contains toxins intended to protect the animal from the dangers that await it in the ocean, but no study demonstrates its toxic nature for humans. In addition to having repulsive skin, it is likely that, like many brightly colored animals, the variegated body of the mandarin dragonet serves as a warning to signal its toxicity.

Where can you observe mandarin fish?

The mandarin fish is found in the warm waters of the southwest Pacific Ocean (from Japan, Philippines, Indonesia to Australia) but also off the coast of New Caledonia. The species lives up to 18 m deep in scree or rocky areas of tropical lagoons, in coral reefs, sheltered lagoons and along the coastline. The cashmere fish moves following the contours of the relief without ever venturing into open water and spends most of its time pecking at microcrustaceans in the interstices of the substrate and living rocks. The mandarin fish often stays near the diadem sea urchins which offer it a certain security: it finds refuge between their long spines and can also nibble on the parasites which are on the skin of the spiny animal. This association therefore benefits both species.

How does the Mandarin dragonet reproduce?

At dusk, the mandarin fish come out of their hiding place to get married. The courtship consists of the male drawing circles around the female, erecting his fins and showing off his most beautiful colors. When his partner allows him, he approaches and lifts her up, placing her pelvises under his. Belly to belly, the couple rises above the substrate to mate, releasing eggs and sperm into the water which fertilize each other. If in the wild, this prolific species is capable of laying eggs almost every evening, its reproduction in captivity is almost impossible for amateurs.

Is cashmere fish a gregarious species?

Given its magnificent livery, the mandarin fish is very popular with aquarists. In captivity, this species can be shy and remain hidden for several days in its shelter. In terms of its sociability, the dragonet is particularly belligerent towards its peers and the males can lead fights that are sometimes fatal. Note that frequent quarrels are also observed within couples. Gathering a school of mandarin fish in an aquarium to contemplate their sublime ballet of colors is therefore not possible. If the relationship is good with other species (preferably reefs), the cashmere fish must be spared too much food competition because, because of its small mouth, it takes a long time to eat. There is no doubt that he will have a large part of his food stolen.

Is Mandarin Fish Easy to Breed?

Synchiropus splendidus can live in an aquarium but due to very specific feeding habits it requires a certain degree of knowledge of marine fish. In the wild, the Mandarin dragonet feeds primarily on small benthic invertebrates such as worms and crustaceans. Specialized stores offer dry foods, flakes and pellets for this type of species, but this is not enough. It is essential to provide the cashmere fish with live prey such as saltwater shrimp or black worms on natural rocks and sand. Some specimens will acclimatize to life in captivity but others never, and will for example refuse any food other than that which they find in the wild. Its breeding is therefore not recommended for beginner aquarists.

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