Clownfish Larvae Rearing with Rotifers: First 14 Days
The first fourteen days after hatch are where clownfish breeding projects succeed or fail. This guide to clownfish larvae rearing rotifers from Gensou Aquascaping in Singapore is written from the perspective of someone who has lost entire clutches to skipped feedings, rotifer crashes, and poorly-timed water changes. Larval clowns do not tolerate mistakes the way juveniles do — a four-hour delay in feeding on day two can wipe out 80% of a batch.
Quick Facts
- Larval tank: 20-40 litres, black walls, bare bottom
- Water: matched to broodstock, 26-27 °C, 1.025 salinity
- First feed: rotifers, morning after hatch, density 5-10 per ml
- Rotifer phase: day 1 through day 7-8
- Brine shrimp (Artemia nauplii): introduced day 5, sole food by day 10
- Metamorphosis: day 8-14, juveniles settle and colour up
- Typical first-clutch survival: 10-30%, improving with practice
Rotifer Culture Before You Spawn
You cannot start a rotifer culture on the day eggs are laid — you need density already rolling. Begin your culture at least two weeks before the expected spawn. We run two 10-litre cultures on a 36-hour harvest cycle, fed RG Complete or live Nannochloropsis, at 25-27 °C with gentle air. A healthy culture looks faintly cloudy, has a slight yeasty smell, and delivers 200-500 rotifers per ml at harvest.
Back-up cultures matter. A single crash with no spare will cost you the clutch. Keep at least two independent bottles.
Day 0: Hatch Night
Clownfish larvae hatch after dark, typically the night of day 7, 8, or 9 after laying. If you are using the tile-transfer method, move the tile to the larval tank two hours before lights out, with an air stone positioned near the eggs to mimic paternal fanning. Cover the tank completely for a full blackout. Do not feed anything yet — larvae live on yolk sac until morning.
Day 1: First Feeding
An hour after lights come on, add rotifers to a density of 5-10 per ml. Check by pipetting 10 ml into a white dish against a dark background. Add live phytoplankton — Nannochloropsis — to green the water to tea-colour, which keeps rotifers nourished in the larval tank and reduces larval aggression. This “greenwater” technique is not optional for clownfish; survival drops by half without it.
Days 2 to 4
Maintain rotifer density at 5-10 per ml with top-ups morning and evening. Keep greenwater steady. No water changes yet — the young larvae are too fragile for siphoning. Light stays on about 16 hours to extend feeding time. Siphon dead larvae off the bottom with a 3 mm rigid tube held still; movement spooks survivors.
Day 5: Introducing Brine Shrimp Nauplii
Newly hatched Artemia nauplii (under 24 hours old, Instar I) are tiny enough for post-flexion larvae. Run two staggered brine shrimp hatcheries so you have fresh nauplii every morning and evening. Hatch at 28 °C, 1.020 salinity, strong aeration, 24 hours. Feed nauplii enriched with Selco once the larvae are taking them reliably, from day 7 onward.
Days 6 to 9: The Crossover
This is the hardest stretch. Larvae are transitioning from rotifers to brine shrimp, some individuals move faster than others, and any gap in food supply causes starvation deaths. Maintain both foods simultaneously. By day 9, most survivors are on brine shrimp exclusively, and rotifer dosing can taper.
Days 10 to 14: Metamorphosis
Stripes begin to appear — a diffuse bar behind the eyes first, then a mid-body bar, then the tail bar. Larvae drop to the bottom and begin behaving like miniature clownfish. Now you can add a sponge filter, begin 10% daily water changes, and introduce crushed pellet alongside brine shrimp. Bodycolour fills in over the following week.
Water Quality Through the Run
Ammonia is the silent killer. Test every second day from day three. If ammonia creeps above 0.1 ppm, perform a slow 10% change matching temperature and salinity to two decimals. Do not use prime or similar dechlorinators in the larval tank — they can bind trace elements rotifers need.
Common Reasons Clutches Fail
Thin rotifer density on day one. No greenwater. Temperature drop from chiller overshoot below 25 °C. Dechlorinator shock. Feeding nauplii too early before larvae are large enough. Noting which failure mode hit each clutch is how you get better — keep a logbook with spawn number, hatch count, and daily mortality.
Singapore Sourcing Notes
Live rotifer starter cultures cost $15-25 on Carousell from local breeders. RG Complete is available from specialist reef shops in Pasir Ris. Brine shrimp eggs run $30-50 per tin of 425 g and last a small hatchery around two months. Nannochloropsis paste ships frozen from regional suppliers — budget for it early.
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emilynakatani
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