Clownfish eggs: spawning signs, hatching timeline, and how to raise the fry

Your clownfish laid eggs. Here is what spawning looks like, how the eggs change day by day, why they hatch after dark, what happens if you leave them in the display, and what it really takes to raise clownfish larvae at home.

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Quick answer
  • A pair of clownfish laying eggs is a sign of healthy, settled fish. The female is the larger fish, and the male tends the eggs.
  • Eggs start bright orange, darken over a few days, then turn silvery as the larvae's eyes develop.
  • They usually hatch about 6 to 10 days after laying, depending on temperature, and always after dark.
  • In a display tank, the larvae are almost always eaten or pulled into filtration. That is normal and harmless.
  • Raising the fry takes a separate larval tank, live rotifers and green water for the first week or so, then baby brine shrimp.

The clownfish pair in our owner's reef tank spawns regularly, so this is a question we get to watch up close. Here is what is going on, backed by the research.

How clownfish pairs work

Clownfish (anemonefish, genus Amphiprion) are protandrous hermaphrodites: every clownfish starts life as a male, and the dominant fish in a group becomes the female. If the female dies, the breeding male changes sex to become the new female, and the next largest fish moves up to breeding male (Fricke & Fricke 1977). Groups keep a strict size order. Smaller fish stay small partly by regulating their own growth so they don't challenge the fish above them (Buston 2003).

This is why two young captive-bred clownfish bought together usually pair up: one grows and becomes female, and the other stays male. It is also why adding a third clownfish to a settled pair often leads to fighting.

Signs your clownfish are about to spawn

Spawning itself usually happens during the day. The female makes repeated passes over the cleaned spot, laying a few eggs at a time, and the male follows behind to fertilize them. It can take an hour or two.

Clownfish egg timeline

A clutch is usually a tight patch of a few hundred to about a thousand eggs, depending on the size and age of the pair. Each egg is a small capsule stuck to the surface at one end. Exact timing depends on temperature, so treat the days below as a guide.

Warmer water speeds development and cooler water slows it, which is one more reason to keep your reef tank temperature steady.

Why clownfish eggs hatch after dark

Clownfish hatching is timed to nightfall, probably because tiny larvae are safer from visual predators in the dark. Lab work on false percula clownfish (Amphiprion ocellaris) showed how that works. Darkness triggers the embryo's hatching glands to release enzymes that soften the egg capsule. Water movement, which the parents supply by fanning the eggs, triggers the larvae's hatching movements so they break out (Yamanaka et al. 2024).

In practice that means eggs often won't hatch under lights or in still water. Breeders who move eggs into a separate tank keep them dark that night and put an air stone next to them to stand in for the father's fanning.

What the parents do

The male does most of the egg care. He fans the clutch with his fins to keep fresh water moving over it and mouths the eggs to clean them, picking off any that turn white. White eggs are unfertilized or dead; a few are normal. The female guards the area and chases off other fish. Feed the pair well while they have eggs, and avoid moving rock or the anemone near the clutch.

New pairs often eat their first clutches, or the clutches don't hatch. This usually settles down after a few spawns.

Leaving the eggs in your display tank

Most reefers do nothing, and that is fine. The eggs hatch at night and the larvae, only a few millimeters long, become food for corals, fish, and filter feeders, or end up in the overflow, protein skimmer, or pumps. The larvae are too few and too small to affect water quality. Some reefers enjoy it as a free live-food feeding for their corals.

If you see eggs, keep doing what you're doing. Stable alkalinity, salinity, and temperature matter more than anything else. Our reef testing schedule and salinity converter help keep things steady.

Raising clownfish fry: what it really takes

Clownfish are among the easiest marine fish to raise, and most clownfish in the hobby are now captive-bred. Even so, the larval stage is demanding. The main problem is food: newly hatched larvae can only eat live prey small enough to fit in their mouths (Olivotto et al. 2011).

  1. Plan ahead. Start a rotifer culture (Brachionus) and get phytoplankton or phytoplankton paste before the eggs are due to hatch. Most first attempts fail because the food isn't ready.
  2. Set up a larval tank. A small bare tank, often 10 to 20 gallons (about 40 to 75 L), with dark sides, a heater, gentle aeration, and no filter intake that could suck up larvae. Fill it with water from the display so salinity and temperature match.
  3. Collect the larvae. Either move the rock, tile, or plug holding the eggs into the larval tank on the evening they are due to hatch, with an air stone beside them, or leave them and scoop up larvae after lights out with a flashlight to attract them.
  4. Days 1 to about 10: keep the water lightly tinted with phytoplankton ("green water") and keep rotifers in the water at all times. The green water feeds the rotifers and helps the larvae see their prey.
  5. From about day 7 to 10: start adding newly hatched brine shrimp (Artemia) nauplii alongside the rotifers.
  6. Metamorphosis: after roughly one to two weeks the larvae settle and start to look like tiny clownfish, with their first white bar. The larval phase of anemonefish in the wild is similarly short compared with many other reef fish (Wellington & Victor 1989).
  7. Weaning: move them gradually onto fine dry foods. Do small, frequent water changes with matched water (our water change calculator helps size them) and siphon uneaten food from the bottom.

Expect losses, especially in the first week and around metamorphosis. If you don't want to culture live food, letting the eggs hatch in the display is a perfectly good choice.

Common problems

New to some of these terms? See the reef glossary.

FAQ

How long does it take clownfish eggs to hatch? Usually about 6 to 10 days after they are laid. Warmer water speeds development and cooler water slows it, so at typical reef temperatures of about 25 to 27 C (77 to 80 F) many pairs' eggs hatch around day 7 or 8. The night of hatching, the eggs look silvery because you can see the larvae's large eyes.

Why are some clownfish eggs turning white? White eggs are usually unfertilized or dead. The male normally picks them off so fungus does not spread to healthy eggs. A few white eggs are normal, especially in a young pair's first clutches. If a whole clutch turns white, the eggs were probably not fertilized, which is common while a new pair is learning.

Will clownfish eggs survive in my reef tank? The eggs usually do, because the parents guard them. The larvae usually don't. They hatch at night as tiny plankton and are eaten by corals, other fish, and filter feeders, or pulled into the overflow, skimmer, and pumps. Leaving them is fine and does not harm the tank.

Do clownfish eat their own eggs? The male regularly mouths the eggs to clean them and removes dead ones, which can look like eating. New pairs sometimes eat a whole clutch, especially after a disturbance. This usually stops as the pair matures.

How often do clownfish lay eggs? An established, well-fed pair often spawns every two to three weeks, and some keep that up for years. Spawning is a good sign that the fish are healthy and settled.

References

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