The mandarin fish is one of the most beautiful fish in the ocean and their special mating display can be seen right here in both Bunaken and Lembeh waters!
• Scientific Name: Synchiropus Splendidus
• Found: Indo-Pacific Ocean (Philippines, Indonesia, Malaysia, Australia)
• Size: 1 -2 Inches
• Diet: Carnivore – feed on small worms, protozoans and small crustaceans
• Habitat: Broken coral rubble beds or under dead coral
• Depth: 1 – 18 metres
Mandarin Fish Features
• The name comes from its fantastic colouration which resembles the robes of an imperial Chinese officer (Mandarin)
• They live in pairs and groups of up to 5
• Males have more orange colouration in their face and are larger in size with an elongated first dorsal spine. Females have smaller dorsal fins.
• Mandarin fish are distinctive due to their unusual shape and broad, depressed head
• One of its most remarkable features is their big outward-set eyes. This is an ideal adaptation for food hunting and feeding in the dim light environments underwater
• They swim with a rapid pulsating of their fins which tends to make them look like they are hovering, like a humming bird
• The mandarin fish is one of the few marine fish which does not have scales. As a protective compensation it is protected by a mucous-coated slimy and smelly skin, which not only protects them from most parasitic skin diseases, but also discourages predators due to its horrible taste. Their bright vivid coloration also serves to give out warning to predators of their nasty smell and taste.
• There is little information on specific predators of this species, although scorpionfish are known to lie in wait to attack an unsuspecting mandarin fish, normally during the mating ritual.
The mating of mandarin fish by spawning is something you HAVE to witness before leaving Bunaken!! Just before the sun sets, 3 to 5 females will make their way to a particular region of reef (“street corner”!) and gather where males visit and display courtship behaviour, hoping to attract the females. The visiting males may tour around various sites in one evening spreading their sperm among a number of different females!
A successful male will be joined by a female that will rest on his pelvic fin. The male and female mandarin fish align themselves belly-to-belly and together, slowly rise about 1 metre above the reef. Once they are at the peak of their ascent, they will release sperm and a cloud of eggs (usually up to 200 eggs). The fish then disappear in a flash. The fertilized eggs are from that point at the mercy of the current and normally take around 18-24 hours to hatch into 1 mm long larvae. For a period of up to 2 weeks they will remain plankton with no parental involvement before finally settling on the reef and choosing an appropriate habitat where they will live for the next 10 to 15 years.
With only a small number of active females in a group’s population, competition among the males is high. In the world of mandarin fish, size does matter! The bigger and stronger males tend to be favoured by females and mate more often than smaller males. Due to the lower chances of mating, the smaller males have developed a rather desperate compensating measure where they rush up to mating pairs and release sperm with the hope of random fertilization!
This is a ritual you can witness most nights here in Bunaken & Lembeh, and is a must for any diving enthusiast – ask your guide for more information!