Green Mandarin Goby (Synchiropus splendidus)

The Green Mandarin Goby (Synchiropus splendidus), properly a dragonet rather than a goby, is arguably the most beautiful fish in the marine hobby. Electric blue, orange, and green swirl across it in a pattern that looks painted on, and it moves in slow deliberate hops across the rockwork with constantly fanning pectoral fins. It is peaceful, completely reef safe, and immune to most of what plagues other marine fish thanks to a thick bitter mucus coat that even deters ich. Browse the rest of our saltwater fish.

Choose Your Size

Feeding, the Part That Decides Everything

In the wild a Mandarin picks at tiny crustaceans continuously from dawn to dusk. To keep one alive you need to replicate that. The three things that actually work, in order:

• A mature tank with real pod habitat. 30 gallons is a technical minimum; in practice you want an established 55 gallons or larger with plenty of live rock and, ideally, a refugium growing pods where the fish cannot reach them.
• Seed the population and keep seeding it. Add live copepods or Tigger-Pods regularly, and feed live phytoplankton so the pods themselves have something to eat and keep breeding.
• Train it onto frozen if you can. Some Mandarins, particularly larger ones and captive-bred stock, will take frozen cyclops, baby brine, or finely chopped mysis. A Mandarin that eats prepared food is a vastly easier animal. Target feed with a baster in a low-flow spot.

Watch the belly, not the behaviour. A healthy Mandarin has a gently rounded profile. A pinched or hollow belly means it is losing, and by the time it looks thin you are already behind.

Care Guide

• Tank size: 30 gallons absolute minimum, 55 gallons and up strongly preferred, with mature live rock.
• Temperament: completely peaceful with other species. Males are territorial with each other, so keep one male per tank. A male and female can share a large system.
• Sexing: males carry a long, spiky first dorsal spine. Females have a short one.
• Reef safe: yes, entirely. It will not touch corals, clams, or ornamental inverts.
• Water: 72 to 78°F, salinity 1.020 to 1.025, pH 8.1 to 8.4. Hardy on water quality, fragile on food.
• Flow: moderate to low. They are weak swimmers with no swim bladder and struggle in heavy current.
• Disease resistance: the mucus coat makes them notably ich resistant, which is part of why they seem bulletproof right up until they are not.
• Tankmates to avoid: anything fast and greedy that strips the water column, and any other dragonet in a smaller tank.

Specifications

Compatibility

Safe with essentially every peaceful reef fish and invert: clownfish, cardinalfish, small gobies, blennies, and dottybacks. Corals, clams, and ornamental shrimp are all fine.

The problem is never aggression, it is competition for pods. Wrasses, especially six-lines and other pod hunters, will strip the same food supply a Mandarin depends on. Keep only one male, and avoid pairing with our other dragonets such as the Spotted Mandarin, Ruby Red Dragonet, or Ocellated Scooter unless the system is large and pod production is genuinely surplus.

Recommended Foods & Supplies

• Bulldawg Copepod Mix, live marine pods blended specifically for Mandarins
• Reef Nutrition Tigger-Pods (Live) to seed and top up the population
• Reef Nutrition Phyto-Feast Live so the pods keep breeding instead of dying out
• SFBB Frozen Mysis Shrimp, finely chopped, if yours learns to take prepared food
• See also the Red Mandarin, the same species in a different colour form

FAQ

Can I keep one in a 30 gallon?
Technically yes, realistically only if that 30 has been running a long time, is full of live rock, and has a refugium feeding it pods. Without a pod source, tank size is not the limiting factor, food is.

How do I know if it is eating?
Watch the belly. A fed Mandarin is gently rounded from the side. A flat or concave belly means it is running down, and that is the point to intervene with live pods or target feeding.

Will it eat frozen food?
Some do, especially larger fish. It is worth trying frozen cyclops, baby brine, or finely chopped mysis from a baster. Never assume it will, though. Plan for pods and treat frozen acceptance as a bonus.

Is it really reef safe?
Completely. It hops across rock hunting microfauna and ignores corals and inverts entirely.

Can I keep two?
One male per tank. Two males will fight. A male and a female can work in a larger system, and pairs will sometimes spawn at dusk.

Why is it called a goby if it is a dragonet?
Just an old trade name that stuck. Synchiropus splendidus is a dragonet, family Callionymidae, not a goby at all. Care information written for gobies does not apply to it.