Mandarin dragonet care

Quick reference

What is a mandarin dragonet?

The mandarin dragonet is a small fish of the western Pacific, from the Ryukyu Islands to Australia, living in shallow lagoons and inshore reefs over silty rubble at 1–18 m.^[6] It isn't a goby, despite the trade name: it belongs to the dragonet family, Callionymidae.^[6] In the wild, and in an aquarium, it spends the day hopping over rock and sand picking off copepods, amphipods and worms, and Meerwasser-Lexikon says it has to eat almost constantly.^[5] At dusk a pair rises toward the surface together to release eggs and sperm.^[6]

Feeding

This is the whole game. Bulk Reef Supply calls feeding the most important part of mandarin care: wild-caught fish often refuse anything other than live copepods, so the tank needs a thriving copepod population, a refugium, or regular additions of live pods, and a mandarin can starve in a tank that looks healthy.^[1] Microcosm warns that one that has grown thin is hard to bring back.^[4]

Captive-bred fish are different. Commercial breeding of the green mandarin became possible through better larval feeds,^[3] and properly weaned captive-bred fish eat inanimate foods: Bulk Reef Supply lists frozen baby brine shrimp, frozen mysis, micro pellets and fish roe,^[1] and Reef Builders filmed Biota's captive-bred pair eating flake.^[7] They still hunt pods between meals.^[1] Mandarins are slow, timid eaters, so target-feed them where faster fish can't steal the food.^{[1, 4]}

We found no reliable figure for how many copepods a mandarin eats a day, or how big a tank must be to grow them, so treat any number you see online as a guess.

Aggression and spacing

Peaceful toward other fish, but males fight: Microcosm says males attack and bite each other, and Meerwasser-Lexikon says two males fight to the death.^{[4, 5]} A male and a female get along, and pairs may spawn in the tank.^{[4, 5]} Bulk Reef Supply advises keeping one, or a mated pair.^[1]

Tankmates

Good with corals and invertebrates.^{[4, 1]} Bulk Reef Supply lists clownfish, gobies, cardinalfish, most wrasses, firefish and tangs as suitable tankmates, but mandarins are timid and easily bullied at feeding time.^[1] The bigger problem is competition for food: in fish-only tanks it often loses out to faster feeders,^[4] and Meerwasser-Lexikon advises against keeping other pod-eaters such as pipefish or small wrasses with it.^[5]

Disease and quarantine

Microcosm calls it highly disease-resistant, and Meerwasser-Lexikon says the mucus covering its scaleless skin may protect it from disease and predators.^{[4, 5]} That isn't immunity, and the commonest cause of death is starvation rather than disease.^[1] We found no disease information specific to the mandarin dragonet. General marine fish guidance applies: CORAL Magazine recommends quarantining every incoming fish, captive-bred included, for at least 2–4 weeks, and UF/IFAS advises 3–6 weeks at 24–27 °C, longer when ich is suspected.^{[10, 11]} A quarantine tank has no pods, so a wild-caught mandarin needs live food there; a captive-bred one already eating frozen food is far easier.^[1]

Breeding

Wild fish spawn as pairs at dusk; females in one study released 12 to 205 eggs, and larvae settled within 14 days at 24–26 °C.^[8] Larval rearing works far better with live copepods: in feeding trials, survival to day 12 rose from about 5.6 % on rotifers alone to about 50 % when copepod nauplii were added.^[9] Captive-bred green mandarins are now produced commercially and reach the trade.^{[3, 7]}

Troubleshooting

Common mistakes

• •Adding it to a new tank with no established pod population.^{[2, 1]}
• •Buying wild-caught fish without a live-food plan.^[1]
• •Keeping two males.^{[4, 5]}
• •Housing it with fast, greedy feeders or other pod-eaters.^{[4, 5]}
• •Waiting until it looks thin to act.^[4]

Equipment & food for this species

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Frozen mysis is a good staple and quality pellets cover daily feeding. Many keepers soak food in a vitamin supplement such as Selcon.

Mandarin dragonet FAQ

Are mandarin dragonets hard to keep?

Wild-caught ones are: LiveAquaria rates the fish difficult, and Bulk Reef Supply says wild fish often refuse anything but live copepods.^{[2, 1]} Captive-bred mandarins weaned onto frozen and pellet foods are much easier.^{[1, 3]}

What do mandarin dragonets eat?

Copepods, amphipods and other tiny invertebrates they pick off rock and sand.^{[5, 4]} Captive-bred fish also eat frozen baby brine shrimp, mysis, micro pellets and fish roe.^[1]

Is a mandarin goby a goby?

No. It's a dragonet, family Callionymidae; "mandarin goby" is a trade name.^[6]

Can you keep two mandarins together?

Only a male and a female. Males fight, sometimes to the death.^{[4, 5]} Males have the longer first dorsal spine.^[2]

What size tank does a mandarin need?

Vendors say 30 gallons and Microcosm 20, for a well-established tank; Meerwasser-Lexikon recommends 240 L (about 63 US gal).^{[2, 1, 4, 5]} We use 75 gallons, because the limit is the tank's live food supply.

Are mandarin dragonets reef safe?

Yes. They don't bother corals or invertebrates.^{[4, 1]}