6 Things I Learned From Breeding Clownfish


Breeding clownfish is a rewarding and educational process. I learned about a bunch of new things during the time I spent raising them. Many of these issues and gotcha-type-situations were barely explained in the popular guides.


I hope that this information will be helpful for anyone embarking on a clownfish breeding adventure. No matter how much you prepare, there will always be something new that catches you by surprise.


Here are some key terms to remember:

  • Fry – Fry refers to the first stage of a clownfish after hatching, fry is more or less interchangeable with the term Larval when it comes to most fish.
  • Rotifers – Rotifers are microscopic animals that reproduce rapidly and make a great food source for most larval fish. Brachionus Plicatilis is a specific type of rotifers that used for feeding clownfish.
  • Phytoplankton – Phytoplankton, Phyto or sometimes called ‘Green Water’, is a class of algae. These single-cell organisms are what you will be feeding your rotifers with.  Nannochloropsis is the most common type of phytoplankton that is used in the breeding process.  However, there are other types that may provide a better overall nutritional profile for your fish.

Clownfish Are Vicious

The mother of my baby clownfish once flew out of my tank in a failed attempt to murder me. Clownfish don’t play around and are very territorial!


I watched their viciousness on a massive scale through the entire clownfish breeding process.


Baby clownfish behavior seems to only have two modes:

  • In a high enough fish per gallon density, they will act like a swarm of bees. The baby clownfish will almost completely stop fighting each other and just focus on feeding and growing.
  • The baby clownfish will endlessly fight over territory and food in a low fish density environment.

This clearly proves that the killer instinct to rip your hand off is deep within their clownfish DNA. Let us all take a moment and be thankful that a clownfish will never grow as large as a shark, or we would really be in trouble…



It can be very troubling to lose most of your clownfish fry to an ammonia spike or food shortage. But, it is even worse to watch the remaining 10-40 of them slowly battle to the death until only a few remain… Can’t we all just get along?

Keeping Rotifers is Harder Than it Looks

Live rotifers are a must-have for anyone breeding clownfish or other species of fish. Rotifers reproduce at a ridiculously fast rate and this means lots of food for your newly hatched clownfish fry, but it isn’t all good news.

Their population growth is both a blessing and a curse. Rotifers will keep reproducing until they foul the water and crash the entire culture. If your rotifers reproduce themselves into extinction, your baby clownfish will likely starve to death. So, running a second culture as a backup is a good idea.

Rotifers also require a lot of maintenance. This usually means daily water changes and feeding the culture with phytoplankton. All of these things can also hit you in your wallet, depending on the scale of your breeding program.

There are some loopholes, like feeding larval copepods to your baby fish. However, any of the rotifer alternatives have massive tradeoffs.

  • Copepods are a much healthier food source than rotifers, but copepods are expensive and reproduce much slower than rotifers. Breeding copepods in the required density for baby fish is a major challenge. Purchasing copepods in the quantities that you will need is going to be very costly, most copepods are available for ~$20 a bottle at your LFS.
  • Starting on day 1 with a premium food for feeding clownfish fry, like Reed’s TDO. The Reed Mariculture feeding chart says you should start feeding the smallest size TDO on day 2. But, it also says you should keep using rotifers until day 11. A few of the biggest clownfish fry might survive without rotifers, but most of the clownfish fry will die from starvation during the first week.

Rotifers are your safest food choice when it comes to breeding clownfish. There is a lot more information on the subject so leave a comment if you’re interested in learning more.

Fighting is More Important than Eating

I have witnessed baby clownfish fighting to the death in a 20 gallon grow out tank during meal time, didn’t I say clownfish were vicious? The dominant clownfish would spend so much effort fighting their tank mates that most of the food would fall to the bottom and go uneaten. They seem to have no interest in any food that hits the floor, so I guess clownfish don’t believe in the 5-second rule?


The most troubling sight was watching the most dominant baby clownfish become an alpha level bully. The clownfish were all from the same clutch of eggs, so their sizes were fairly consistent. However, an alpha always seems to emerge in every tank.


This self-ordained king of the tank will fight all the other clownfish for territory and food. The bully will expend more energy fighting than eating and eventually become weak. This weakness will usually lead to the alpha being killed by the next toughest baby clownfish in the aquarium.


Absolute power corrupts absolutely in the hearts of men and fish alike. Once the challenger has killed the current alpha level bully, he will quickly take their place and the cycle begins again. This is why we can’t have nice things!


Packing dozens or even hundreds of clownfish into a tiny space is the best solution to this problem. They will be too busy being jammed together like sardines to try and kill each other. Your instinct will be to give them a spacious home to grow and thrive, but this will only lead to their ultimate demise, Lord of the Flies style.

Size Matters!

Mixing different sizes of baby clownfish in the same grow out tank often ends in tragedy. You can get away with mixing juvenile clownfish if they hatched within a few weeks of another clutch, but more than that is pushing your luck.


The natural tendency of almost any fish is to bully and kill any similar fish that is smaller. The larger fish do not understand that you have a year worth of yummy food for everyone in your supply closet. The larger fish only sees the smaller guy as a threat to their food supply. Feeding them extremely well can lesson this type of bullying, but it is near impossible to override their genetic survival skills. Overfeeding will also lead to poor water quality and that has its own set of problems.


The size of the tank used to hatch, raise and grow out your clown fry in is also very important. You must select a tank that is large enough to hold a stable water temperature and provides healthy water parameters. The tank should also be small enough to keep the density of rotifers and clownfish fry high enough or you will suffer causalities

Always Use Quality Food

When it comes to raising clownfish, the best food to use is definitely TDO from Reed Mariculture.  Freshly hatched brine shrimp and dry Hatchery Diet from Sustainable Aquatics are other food options, but TDO is the champ.


The only downside of TDO has always been its limited availability.  Thankfully, Bulk Reef Supply has started to stock it and I even saw some at my LFS.  TDO is always available directly from Reed, but the shipping prices are painfully high.


High-quality food is very important to your rotifers too.  Rotifers are only as nutritious as the last meal they ate.  Clownfish fry require the nutrition from phytoplankton to grow, but the babies will not eat straight phyto.  So, we feed phyto to the rotifers and then feed the gut loaded rotifers to the clownfish fry, kind of like hiding a pill in peanut butter for your dog.

Lighting a Clownfish Hatching Tank isn’t Simple Either

Things are getting exciting!  You have all your rotifers ready to go and the eggs are about to hatch, so what now?


Hatch night requires the tank to be in total darkness.  Clownfish eggs are hardwired to hatch in the dead of night as a defense mechanism for avoiding predators.  Any fish in the area would quickly make a meal of the fry the moment they hatch if it was daytime.


After all the eggs hatch, you will need to slowly introduce them to a light source. Newly hatched clownfish fry can survive for the first day without food with the yolk from their egg, but they will need to hunt for live food soon.


I dare you to try and hunt for a bowl of cereal in total darkness.  It would probably end in heartbreak and a huge mess all over your kitchen.  The solution sounds simple: Just turn on a light so you can actually see what you’re doing!


There is one catch with that plan… Your eyes have never seen light before and you can literally die if the light is too intense.  Sounds fun, doesn’t it?


This is the struggle of raising clownfish fry during the first week.  You must provide enough light for them to see their food, but no too much light or they will die from the stress.


Clownfish fry will cling to the corners of the tank or frantically swim in a circle when exposed to too much light.  The circular swimming pattern is almost comical until you realize that stress from the light is fatal.


The first week will be a constant battle to find the sweet spot for the light.  You can use phyto to tint the water and it will reduce the light penetration.  However, it is constantly eaten by the rotifers and the tint amount will change through the day.  The light may be perfect in the morning, but fatally bright by dinner time.

Clownfish Breeding Conclusions

Breeding clownfish is not as simple or as complicated as a lot of the books and guides make it sound.  I found the difficulty level to be right about in the middle of my expectations and some mistakes were unavoidable.  You can read dozens of books, but nothing will totally prepare you for bringing new marine life into your home.


Clownfish are a prolific spawning fish and will give you many opportunities to practice your breeding skills.  Most clownfish will lay eggs like clockwork, almost every week.


Don’t beat yourself up about losing batches of baby clowns at first, because the eggs would have had a 0% chance of survival in your display tank.  You are giving their offspring a fighting chance at life by even attempting to raise them.  Any eggs that hatch in a normal aquarium will either be quickly eaten or killed by your filtration.


This list only represents a small sample of the lessons that I learned from my clownfish breeding adventure.  Leave a comment and share your own experiences and if you enjoyed this list and would like me to write a follow-up, you can leave a comment about that too.


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Phil Beauregard

Phil Beauregard

A man with a beard, that you can trust! Phil Beauregard is a business consultant and entrepreneur that has been addicted to fish keeping since childhood. He grew up with stories of his grandfather’s exploits during the early days of reef aquariums and African Cichlid breeding. Phil brings a flair for high tech DIY projects and his love of teaching others to the reefing community.

3 thoughts on “6 Things I Learned From Breeding Clownfish”

  1. I’ve been breeding clownfish a little over a year now and I would say the biggest hurtle is lighting fry tank for the 1st 3 days. I’ve lost complete hatches to this . Every egg hatches lots and lots of fry in tank tint water add rots just to come home after work to find them all dead from to much light. So 1st day I tint just enough that I can’t see the bottom of tank and only give ambien light. I also put a cover over 1/3 of tank so fry can hide in the dark if needed. Or at least that’s the theory. I found this to be an enjoyable read . Didn’t know about the more fish pr gallon would help with fighting.

  2. Christian Schmidt

    Great article. Well written and lots of awesome info about these little murderers. I do have a handful of questions. I’ve been “breeding” clownfish off and on for a few years my father before me. So you’d think I’d have it down. I’ve been successful raising them to sellable fish size once…. no I’m not in it to make money… That’s one fish out of hundreds of eggs. I’ve purchased a ton of rotifers a ton of green water raised phyto and spent hundreds of dollars and hours on this little “hobby”. I’d say it’s getting the larval past the first few days is my biggest obstacle. I do have three fish from my first batch growing out in a grow out tank. From the first clutch that I wasn’t ready for at all.. I’ve recently gotten them to lay on a pot so I don’t have to use my larval catching contraption any more. Though the larval seem to be stronger when I let them hatch in display tank?‍♂️. Non the less I’ve tried 5 gallon square tank 10gallon square tank and just recently a black pail those all died on the second night? Most success I guess was my 5 gallon tank so maybe I answered my own question but 3 babies out of hundreds? Is that normal. What type of container do you put the larval in for the first week?
    I would really appreciate any info and I’ll try not to be one of those obnoxious ask a milli9n more questions type of people?

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