Synchiropus splendidus

Synchiropus splendidus

The mandarin fish (Synchiropus splendidus Herre, 1927) is a saltwater fish belonging to the Callionymidae family.

Systematic –
Eukaryota domain,
Kingdom Animalia,
Phylum Chordata,
Class Actinopterygii,
Order Perciformes,
Suborder Callionymoidei,
Callionymidae family,
Genus Synchiropus,
Species S. splendidus.
It’s basionym the term:
– Callionymus splendidus Herre, 1927.
The terms are synonymous:
– Neosynchiropus splendidus (Herre, 1927);
– Pterosynchiropus splendidus (Herre, 1927).

Geographic Distribution and Habitat –
The Synchiropus splendidus is a fish found throughout the Indo-Western Pacific Ocean, from the Ryukyu Islands (Japan) to southern Australia. It is also present in countries such as the Philippines, Indonesia, Papua New Guinea, Palau, Micronesia, New Caledonia, and Solomon Islands.
Its marine habitat is sheltered coastal lagoons and inshore coral reefs, often among sand, rocks, and coral debris, at depths between 1 and 18 m.

Descrizione –
The Synchiropus splendidus is a small fish, approximately 6–7 cm (maximum about 8 cm, especially for males).
Its body is cylindrical, with a triangular head and protruding eyes and a protractile mouth.
Its coloration is extraordinary; it has a bright blue background with wavy orange, red, or yellow streaks. Its ventral fins (resembling legs) are used for “walking” on the seabed. Some rare variants have a red background with black stripes.
It is one of the very few vertebrate species whose blue color is due to cellular pigments (cyanophores) and not only in its optical structure.
Its epidermis is scaleless and covered with a slimy, slightly poisonous mucosa, which serves as a defense against predators and parasites.
It exhibits sexual dimorphism: the male has a taller and longer first dorsal fin.

Biology –
The Synchiropus splendidus prefers habitats with branching corals and live rock, where it can find microfauna to feed on.
Mandarinfish mate at night: the pair emerges from their hiding corals, suddenly swims upward, and then both male and female release eggs and sperm simultaneously.
Reproduction occurs through a unique mechanism: at nightfall, pairs or groups approach each other, ascend in a spiral, and, as mentioned, release eggs and sperm simultaneously. A female lays approximately 200 eggs (once per night), with external fertilization.
The larvae are born pelagic, take a few days to develop fins and assume juvenile form, and reach adulthood within a few weeks.
This species has a longevity, living 10–15 years near coral reefs, but in captivity it rarely exceeds 2–4 years, primarily due to the difficulty of adequate nutrition.

Ecological Role –
Synchiropus splendidus was described by Herre in 1927, originally as Callionymus splendidus (which is, in fact, its basionym).
The genus name derives from the Greek syn- (together), chiropus (hand-foot), referring to its small, leg-like ventral fins. The epithet splendidus means “splendid” in Latin.
It is a diurnal fish, often solitary, but also found in pairs or small schools.
It is a social animal that lives in pairs or large schools of about 40 individuals. The male has only a protective role, as whenever a predator approaches the school, this fish will perform a series of intimidating actions, such as raising its majestic dorsal fin.
It is a benthic predator of microinvertebrates—copepods, amphipods, polychaetes, small gastropods, fish eggs, and ostracods—on which it feeds practically all day in its territory of a few square meters.
For this reason, it is a predator of microinvertebrates that helps regulate these populations in coral reefs and is an indicator of the health of these habitats; Its survival depends on the availability of these microhabitats and natural prey.
The mandarinfish’s size and attractive coloration have made it a popular saltwater aquarium fish. It is recommended to only keep it in established tanks so that it can access existing microfauna to feed on.
However, despite being highly sought-after in aquariums, it is a difficult species to maintain, requiring mature tanks rich in live microfauna. Its presence can highlight the ecological quality of the habitat.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Louisy P., 2016. Identification Guide for Marine Fish of Europe and the Mediterranean. Il Castello Editore, Milan.

Photo Source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/31233686/original.jpg