The green mandarin dragonette (Synchiropus splendidus) is one of the most beautiful fish you can put in a reef tank. It's also one of the most heartbreaking. Most mandarins sold in Australia don't make it past their first six months in captivity, and the reason is almost always the same: they slowly starve to death.
This is fixable. But you need to understand what they actually eat, and commit to feeding them properly before you bring one home.
Why mandarins are different
Mandarins are dragonettes (family Callionymidae), not gobies, despite the common name "mandarin goby". They have small mouths, slow methodical hunting behaviour, and an instinct tuned tightly to live, moving prey. In the wild, they spend most of the day picking copepods and small invertebrates off rockwork and substrate.
Most won't accept dry pellets, freeze-dried, or even frozen mysis. Some can be trained onto frozen food after weeks of effort, but you can't count on it. If you bring a mandarin home expecting it to eat what your other fish eat, you've already made the most common mistake in the hobby.
What they actually need
The short answer: live copepods. Lots of them, every day, for the rest of the fish's life.
The longer answer depends on your setup. Here's what works.
- Tisbe biminiensis. Benthic, surface-dwelling copepods that live on rockwork and glass. Mandarins love them. Tisbe also breed readily in a refugium, which is exactly what you want.
- Apocyclops panamensis. Smaller pelagic copepods that swim in the water column. Good for variety and for fish that prefer hunting in open water.
- Tigriopus californicus or T. australis. Larger, slower, and red-orange in colour. Easy to spot for a hungry mandarin and high in carotenoids.
Amphipods and the occasional small mysid will also be eaten, but copepods are the staple. A healthy mandarin should be hunting almost constantly during the lights-on period.
The pod problem
Here's where most reef-keepers go wrong. They buy a mandarin, dose a single bottle of pods, and assume the population will sustain itself. It almost never does. A hungry mandarin can clear out a small pod population in days, and without somewhere safe for the pods to breed, the supply collapses.
The fix is a productive refugium. Not a small one bolted onto the back of a nano. A proper refugium with macroalgae (chaeto works well), live rock rubble, and minimal flow. This becomes a copepod factory that the mandarin can't access directly. Pods breed in the refugium, get carried into the display by the return pump, and the mandarin picks them off as they arrive.
If your tank doesn't have a refugium, or the refugium is small, you'll need to dose live copepods regularly. Weekly is the minimum. Twice a week is better.
How to actually feed one
- Establish the pod population first. Run your refugium for 4 to 6 weeks before adding the mandarin. Dose pods early, feed phyto, and let the population build.
- Dose at lights-out. Adding pods after dark gives them time to settle and hide before the mandarin starts hunting.
- Watch the body shape. A well-fed mandarin has a rounded belly. A starving one shows a sunken stomach and visible spinal ridges. Once that ridge appears, you have weeks at most.
- Don't house multiple mandarins in a small tank. They'll compete for limited pod populations and one will lose. Minimum tank size for a single mandarin is around 200 L, and that's tight.
What about live brine shrimp?
Live brine shrimp can supplement the diet and are sometimes useful for transitioning a mandarin onto more readily available foods. But brine shrimp on their own are nutritionally hollow. They have to be gut-loaded with phytoplankton to be worth anything, and even then they're a supplement, not a replacement for copepods.
The bottom line
Mandarins are not beginner fish. They're not even intermediate fish. They're a commitment. If you can't run a productive refugium or commit to weekly live food deliveries, don't buy one. They deserve better, and so does your wallet.
Get the setup right and you'll have one of the most rewarding fish in the hobby. Hardy, peaceful, and content to hunt for years on a steady supply of pods.
