Spotted Mandarin Dragonet (Green Mandarin)
Synchiropus picturatus
This little dragonet is basically a living piece of reef art-chunky fins, goofy "hovering" swimming, and those crazy psychedelic spots that look painted on. The big thing with them is they're constant pickers, cruising rockwork all day hunting tiny critters, so they're happiest in a mature tank with tons of pods (or a keeper who's ready to meet them halfway on food). If you like chill fish with tons of personality that don't bother anyone, mandarin time is hard to beat.
The Spotted Mandarin Dragonet features vibrant, multicolored patterns with striking blue-green and orange scales, showcasing elongated dorsal fins.
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Quick Facts
Size
3 inches
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
30 gallons
Lifespan
10-15 years
Origin
Western Pacific (Philippines, Indonesia, surrounding reefs)
Diet
Carnivore/micro-predator - mainly copepods and other tiny crustaceans; some individuals can be trained onto frozen (mysis, brine) and prepared foods
Water Parameters
24-27°C
8.1-8.4
8-12 dGH
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Calculate heater sizeCare Notes
- Don't drop a spotted mandarin into a new tank-wait until the tank is mature (think 6+ months) with lots of live rock and a healthy pod population, or it'll slowly starve even if it looks "fine" at first.
- Keep it in a bigger, stable system (30-40g+ minimum, bigger is easier) with lots of nooks; they cruise the rock all day and hate big swings more than they hate "slightly off" numbers.
- Aim for reef-normal water: 75-79°F, salinity 1.025-1.026, pH ~8.1-8.4; keep nitrates low-ish (like <10-20 ppm) and avoid sudden salinity/temp changes during top-off or water changes.
- Feeding is the whole game: live copepods are their bread and butter, so either run a refugium/pod hotel and seed pods regularly, or be ready to culture pods at home.
- If you want to convert it to prepared foods, try multiple small feedings of enriched live baby brine first, then mix in frozen (Cyclops, finely chopped mysis/roe); a feeding dish helps keep food from blowing away.
- Skip tankmates that compete for pods or harass it-sixlines, melanurus/other wrasses, scooter 'blennies' (also dragonets), and fast, pushy eaters will outcompete it hard.
- They're usually chill with peaceful reef fish and won't bother corals, but cover intakes/overflows-mandarins are clumsy perchers and can get pinned to strong suction.
- Breeding is doable in a calm tank: a well-fed male/female pair will do a dusk "rise and spawn," but the eggs/larvae are tiny and need live plankton (rotifers/copepod nauplii) or they won't make it.
Compatibility
Good Tankmates
- Peaceful gobies (watchman goby, neon goby, clown goby) - they mostly mind their own business and don't compete too hard for the same food if you're feeding the mandarin properly
- Small, chill blennies (tailspot blenny, barnacle blenny) - generally good neighbors and they won't hassle a mandarin cruising the rockwork
- Reef-safe wrasses that aren't bullies (fairy/flasher wrasses) - active but usually not mean, and they won't sit on the sand waiting to ambush the mandarin
- Clownfish (ocellaris/percula) - most pairs are fine; they tend to stick to their corner and ignore mandarins
- Cardinals (banggai or pajama) - slow, peaceful, and don't mess with mandarins; nice calm midwater fish
- Small reef-safe anthias in a well-fed tank (like a single lyretail in a bigger setup) - generally peaceful, just keep feeding frequent so the mandarin still gets its share
Avoid
- Other mandarins/dragonets (especially same species or two males) - they can get territorial and you'll see chasing; plus you're doubling the pod demand
- Pod-hogs that outcompete them (six-line wrasse, some leopard wrasses, scooters/other dragonets) - mandarins are slow pickers and can get outpaced hard
- Aggressive/nippy stuff (damsels, dottybacks, some hawkfish) - they'll harass a mandarin or just stress it out when it's trying to graze
- Big boisterous eaters (bigger triggers, puffers, large wrasses) - not always 'mean' but they turn feeding time into a riot and the mandarin loses out
Where they come from
Spotted mandarins (Synchiropus picturatus) come from shallow reefs and rubble zones in the Indo-Pacific—places packed with tiny crustaceans crawling all over the rock. That’s basically their whole lifestyle: slow cruise, peck-peck-peck, all day.
They’re not open-water fish. Think “reef floor forager” that lives in a buffet of microfauna.
Setting up their tank
If you want to succeed with a spotted mandarin, build the tank around food availability, not around gallons. I’ve seen them do fine in modest-sized reefs, and I’ve seen them waste away in big, “perfect-looking” tanks that were too sterile.
- Mature tank: aim for 6+ months old, longer if the rock started “dry”
- Lots of live rock and nooks: they hunt on surfaces all day
- A refugium helps a ton: macroalgae + rubble = pod factory
- Gentle-to-moderate flow near the bottom: they don’t love being blasted around
- Covered top: they usually don’t jump like wrasses, but startled fish do weird things
New tank + mandarin is a classic heartbreak combo. Even if the fish looks fine the first couple weeks, the slow starvation often shows up later.
Sand bed isn’t mandatory, but I like a little sand and rubble because it gives pods more places to reproduce. The big deal is having a constant supply of copepods/other micro-critters that aren’t getting vacuumed up by aggressive pod-hunters.
What to feed them
In the wild they’re basically living pipettes for copepods. In your tank, the gold standard is a fish that actively hunts pods AND will take prepared foods. Some do. Some never really do. Plan for the “pods only” scenario so you’re not stuck.
- Copepods (live): your main safety net—Tigriopus and Tisbe are common choices
- Live baby brine (enriched) and live brine: sometimes helps bridge picky fish onto frozen
- Frozen foods: mysis (small), calanus, finely chopped seafood—some will learn
- Pellets: a few individuals accept tiny sinking pellets, but don’t count on it
Target feeding can work if you’re patient. I’ve had better luck using a feeding dish (a little glass/ceramic bowl on the sand) and dropping in small frozen foods at the same time every day. They learn where the “free stuff” shows up.
If you’re relying on pods, seed the tank heavily and keep replenishing. A single mandarin can mow through a surprising amount. If you add one to a tank with a thin pod population, it’s like putting a goat in a small yard—looks fine until there’s nothing left.
Watch body condition, not just behavior. Mandarins still “hunt” even when they’re losing weight. A pinched belly behind the pectoral fins is your early red flag.
Behavior and tankmates
They’re peaceful, slow, and kind of oblivious. Most of the day is spent scooting along the rock, picking at tiny prey. They don’t compete well at feeding time, and they won’t defend themselves from pushy fish.
- Good tankmates: chill gobies, blennies, clownfish, cardinals, dartfish, many reef-safe inverts
- Be careful with: wrasses and other pod hunters (six-lines, some Halichoeres), scooter “blennies”/dragonets, dottybacks, hawkfish
- Avoid: aggressive eaters that will dominate the tank and stress them out
Two mandarins can work, but it’s not automatic. A male/female pair is the usual goal. Two males often spar and one loses access to food.
Sexing: males have a taller, more dramatic first dorsal spine (“sail”). Females look a bit more understated. If you’re trying for a pair, pick the fish in person if possible.
Breeding tips
They’re one of the cooler reef fish to watch courtship-wise. Healthy pairs often do a dusk “rise” into the water column, release eggs and milt, and then drop back down like nothing happened.
If you see the dusk rise, you’re doing something right: stable tank, well-fed fish, and low stress. Try not to blast the lights on/off suddenly around that time.
Raising the babies is the hard part. The larvae are tiny and need specialized live foods (think rotifers and then copepod nauplii) and very clean, stable rearing setups. Fun project if you’re already into culturing live foods, but not a casual “oh I’ll just try it” situation.
Common problems to watch for
- Slow starvation (most common): hunting all day but getting thinner over weeks
- Pod competition: tankmates outcompete them even if the tank looks “busy with pods” at night
- Getting bullied off the rockwork: subtle stress, hiding more, less hunting
- Shipping/collection stress: some arrive already underweight—those are tough turnarounds
- Disease masking: their slime coat helps, but they can still get parasites; don’t assume they’re magically immune
Don’t buy one with a pinched belly thinking you’ll “fatten it up later.” Start with a fish that looks round and alert, actively pecking, and ideally already eating frozen at the store.
If your mandarin starts hanging out in the open but pecking less, or the belly line starts looking sucked in, act fast: add pods, reduce competition, and start a predictable feeding routine with a dish. They don’t bounce back overnight, but they can recover if you catch it early.
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