Mandarin Dragonet
Synchiropus splendidus
Strikingly coloured fish needing a copepod-rich tankAdvanced
- Lifespan
- 5-10 years
- Size
- 6-8cm (2.5-3in)
- Social needs
- One male per tank; a female may be added
- Time
- High
- Cost
- High
- Diet
- Carnivore, live copepods primarily
Overview
What is this animal?
- The Mandarin Dragonet is a strikingly coloured fish, swirled in green, orange, and blue.
- Despite its calm, slow-moving charm, it is an advanced fish because of its specialised diet of small live invertebrates, mainly copepods.
- Most mandarins die slowly of starvation in tanks that cannot sustain a copepod population.
- Success needs a large, mature reef, ideally with a refugium, and patience to establish a thriving food supply.
Temperament
- Peaceful, slow, and shy, it spends the day methodically hopping across rock and sand hunting pods.
- It is reef-safe and harmless to corals and invertebrates, making a calm community fish.
- Males are territorial toward other males, so keep only one male per tank; a male and female can coexist in a large system.
- Avoid fast, greedy tankmates that outcompete it for food.
A good fit for
- Experienced keepers with mature reefs
- Tanks with a refugium and pod culture
- Aquarists who choose captive-bred, feeding stock
- Patient hobbyists with peaceful communities
Common mistakes to avoid
- Starves without an established copepod supply
- Sold for immature tanks that cannot feed it
- Watch for a pinched, hollow belly
- Greedy tankmates outcompete this slow feeder
Enclosure
Minimum 200 litres (53 US gallons)
Must be housed alone. One male per tank; a female may be added
- Provide a well-established reef of at least 200L (55 gallons), and realistically larger, with abundant live rock and a sandbed that hosts copepods.
- A refugium or pod-culturing system is strongly recommended to replenish the food supply.
- Keep temperature 24-27C (75-81F), salinity 1.024-1.026, pH 8.1-8.4, and ammonia and nitrite at zero.
- The tank must be biologically mature, never new, before a mandarin is introduced.
Supplies
Setup
- Tank, stand and sump
- Return pump and powerheads
- Protein skimmer
- Reef lighting
- Rock and sand
- Salt mix, refractometer and test kits
- Quarantine tank
Ongoing
- Live copepod bottles for regular top-ups
- Refugium or pod-culture setup
- Refugium macroalgae or pod hotel media
- Frozen cyclops and baby brine shrimp (for trained individuals)
- Small marine pellets (for trained individuals)
- Turkey baster for target-feeding near the rockwork
- Small thawing cup
Safe substrate: Aragonite sand · Dry or cured live rock · Bare bottom
Care routine
Daily
- Check salinity, temperature and flow
- Head-count and look everyone over
- Target-feed several times a day
- Top up evaporation with fresh water
Weekly
- Service the skimmer and filter socksevery 3 days
- Check the copepod population
- Clean the glass
- Test the water
Monthly
- Water changeevery 2 weeks
- Calibrate the refractometer
- Check salt, RO/DI and reagents
- Harvest and refresh the refugium
Less often
- Deep-clean pumps and powerheadsevery 3 months
- Replace RO/DI filter mediaevery 6 months
Vet: Monthly pod and belly-profile check — every 1 months
Top resources for more info
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Diet
- A specialised carnivore that grazes copepods and amphipods picked from rock and sand throughout the day.
- A single fish can quickly exhaust a tank's pod population, so a refugium and regular pod top-ups are important.
- Many individuals never accept prepared food, though some can be trained onto frozen cyclops, baby brine, or pellets, and captive-bred mandarins take prepared diets more readily.
- Choose feeding specimens whenever possible.
Health
- When properly fed, mandarins are reasonably hardy and resistant to ich thanks to a thick protective slime coat.
- The main health risk is slow starvation, visible as a pinched belly and hollow stomach over weeks.
- Quarantine and stable water remain important, but the single best safeguard is confirming the fish eats and maintaining a robust food supply.
- A plump, rounded belly indicates a thriving mandarin.
Is your enclosure big enough?
Is this urgent?
In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.
Go now
Today
Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
In a marine system the rock and the sand are life support, and how you start them decides the first six months.
Safe
With a caveat
Never
This is our general list for saltwater fish. We have not built one specific to Dragonets yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Other Saltwater Fish worth knowing
Same axes, same care guides — the honest way to compare them.
Browse all Saltwater Fish →
