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Old 09/11/2003, 01:10 AM
JHardman JHardman is offline
Rare Clownfish Freak
Join Date: Jan 2003
Location: Phoenix AZ
Posts: 6,035
My Clownfish just laid eggs. Now what?

It is a fairly common occurrence for clownfish that we keep in our tanks to spawn. But for the aquarist that wants to raise those clownfish it is often very stressful time with the question of “What do I do now?� screaming in their head.

My first and best recommendation is to get a copy of Joyce Wilkerson’s book “Clownfishes: A guide to their captive care, breeding and natural history�. The subject of breeding and raising clownfish is a long one that is not well suited to “writing a book� in a thread.

First let’s get a little bit of information out there so you will be better informed about what is going on and what will happen.

Clownfish are the Swiss clocks of the marine fish world.

Clownfish have a very acute sense of time. They know when to wake up, go to bed, eat and even spawn. Clownfish on average will spawn 2.3 times per month. Once a pair starts spawning this regular spawning activity can continue for many years to come.

Typically clownfish will lay their nests with a cycle of about 13 to 15 days between spawns. However this is not always the case. Each pair of clownfish will have their own cycle. And some pairs are just broken clocks that can not keep a regular cycle if their lives depended on it. For example I have a pair of A. Ocellaris that lay anywhere from 7 to 14 days. But most pairs will be pretty regular.

Pair of A. ocellaris spawning, first the is of the female making her pass, the second the male making his pass.

Clownfish will typically spawn at the same time of day each time too. Some spawn in the morning hours, some in the evening, but most will spawn in the afternoon hours. Once you know your pairs special time, you should avoid interrupting them from their business. No peaking. Some pairs are very tolerant of people/movement around their tank while spawning, some will stop or even consume the eggs laid already if they are disturbed during spawning. Most however will be somewhere in the middle, just stopping long enough to see what you are up to, rather you are going to feed them or not and will return to the dance as soon as you leave the area.

Even the eggs know what time it is!

Yes you read that right; even the eggs know what time it is. The eggs will hatch in 5 to 10 days. The time it takes for the eggs to incubate and hatch is dependant on the water temp of the tank. The warmer the water the faster the eggs will incubate and hatch. At 82°F most eggs will hatch in 7 or 8 days. This is a ideal time, because if the eggs hatch in much more than about 8 or 9 days the yolk sack will be depleted and reduce the time that a larva has to learn to hunt for food and eat. Sooner than 7 days are there is a higher mortality rate in the larva. I suspect that it is do to under developed eyes.

The eggs will start to hatch a couple hours after lights out on their day. Some species and even some pair’s eggs are very sensitive to light. Some nests will hatch in a slightly dimmed room, while others will delay hatching for a day if the slightest bit of light is present.

Clownfish eggs

Clownfish eggs are laid in a more or less circular pattern, but this can very greatly depending on what they are laid on. Clownfish eggs when freshly laid will be more or less the primary color of the parents. For A. Ocellaris or A. Percula eggs for example will be a bright orange, but the eggs of a maroon or tomato clownfish will be more red. As the eggs mature they will slowly turn darker ending up almost completely black by the third to fifth day. As the eggs mature the eggs will start to become clear with two small silver or bronze dots which are the eyes reflecting light. When you see the eyes, you will know that hatching is not far off. When the eyes reflect more of bronze color they will hatch that night. It can be tough to see this color of reflection if you can not look at the correct angle.

The good eggs will stay attached to the substrate. Bad eggs will be picked off by the parents. If by some chance the parents don’t pick off the bad ones, they will turn white and generally will fall off the substrate. Infertile eggs will turn white in a couples days.

It is primarily the job of the male to tend the eggs and care for them. It is primarily the female’s job to protect her mate and the nest. But both will share each others duties. The male will spend most of his time fanning and mouthing the eggs, this keeps them aerated and clean. A dedicated male can even forget to eat, so sometimes you may need to target feed him, if he will take food. There are of course exceptions to this pattern too. Some maroon females will tend and defend the nest, especially with the large size of maroon nests.

Freshly laid A. ocellaris eggs.

Clownfish are picky about their nesting site and tank

As I have stated before clownfish will continue to spawn for years to come once they start spawning. However there are a few things that you need to be aware of that could stop them from spawning or severely disrupt their cycle.

First your pair is now expending quite a bit more energy now that they are spawning. You will need to increase the amount of food you are feeding, especially between spawns. If the pair gets malnourished they could stop spawning, or consume their nests, or produce unviable larva, or become stressed and vulnerable to parasites and disease.

Second clownfish do not like things that change. Be aware that you could throw your pair off by changing things in and around your tank. Something as simple as adding a new lighting system, adding something to the tank like a coral, or even adding a new piece of furniture in the room where the tank is could throw your pair off their cycle. Stability is the key here. Don’t change the lighting cycle, avoid adding or rearranging things in the tank or room. Some pairs can tolerate just about anything, others can be thrown off by the simplest of things. The good news is that the most common species kept in the hobby are fairly tolerant of changes and will resume their spawning cycle once they are comfortable again.

Food for clownfish larva and fry

The first food for clownfish larva is fortified L-Strain rotifers. Rotifers are small phytoplankton eating zooplankton. In a dense culture of rotifers they resemble small specs of dust in the water column. Several people and hatcheries have tried to find a non living first food for clownfish larva, but to date none has been found that can really be considered successful. So unless you are willing to live with survival rates below 30% forget about non live first foods. Rotifers are not difficult or expensive to culture at home, but it can be more than someone wants to go through to raise a single batch or two of eggs.

The second food offered to clownfish larva and fry is BBS (Baby Brine Shrimp).

With second food sources there has been some excellent progress made in using non living foods. Many home based breeders are now using Cyclop-eeze as their sole source for a second food source or as a supplement to BBS.

For more information on culturing rotifers and phytoplankton please refer to Dr. Frank Marini’s excellent set of articles here…

For more information on Cyclop-eeze The only online source I am aware of to purchase Cyclop-eeze is Some LFS are carrying Cyclop-eeze now, so it is worth a call to see if you can get locally.

It is also possible to purchase live rotifers and phytoplankton paste from online sources too, but the cost can be prohibitive. Your little sea piglets can eat an amazing amount of rotifers in a very short period of time.

Now for the bad news

Chances are very good that when you first see the nest that you will not have enough live fortified rotifers and phytoplankton to fortify and grow rotifers to make an attempt at raising the first batch or two of eggs. And to add insult to injury, you do not have enough time to grow enough rotifers and phytoplankton to raise the first batch either.

But don’t be too distressed, remember clownfish are the Swiss clocks of the marine fish world and you will have lots of chances in the future to try your hand at raising clownfish.

Now for the details

The larval or rearing tank
A 10 gallon or 5 gallon tank is likely the most commonly used tank size for rearing larva and fry. You will need the following items to prepare your rearing tank for the day of hatching.

Small heater with the indicator light taped over so that it does not shine in the tank. I use plain old electrical tape. After a few days you can remove the tape if you want to.

You will want a thermometer of some kind that is fairly accurate to keep an eye on the tank temps. I like the small digital ones with the remote probe. They are cheap, easy to use and fairly accurate.

A couple of air stones and an air pump. You will use the air stones for two things. First you will want one under the heater to keep water moving over the heater and to keep the larva away which are attracted to the heat and will cook or asphyxiate in the hot water around the heater. It will also provide water movement in the tank throughout the rearing process. Personally I like the long paper or stone air stones that have a couple of suction cups on them. They can be easily placed directly under the heater and still not interfere with your chores in the tank. I like to place the heater in a horizontal position in the tank so that I can use the least amount of water possible in the tank. The second will be used to aerate the eggs prior to hatching.

Next you will need some white paper to cover the outside bottom of the tank. This will help with the lighting in the tank which is critical and also give you a good contrasting background to clean the bottom, estimate rotifer density and phytoplankton density.

Next you will need some dark paper that is dense enough not to let light through it. I use black construction paper. Cover the four sides of the tank (on the outside). You do not want any cracks or gaps where light can enter the tank from the side. Clownfish larvas are touchy when it comes to lighting and have not evolved to deal with side lighting like we have in our tanks.

Next you will need a light source that you can adjust the height of. I use a NO florescent light about 8� above the height of a standard 10 gallon tank. To adjust the intensity of the light in the tank I use paper towels laid over the top of the tank.

You will want to put water from the parent’s tank into the rearing tank the day of hatching. Get all of your parts and pieces hooked up and working. The last thing you want to do is find out that the heater is too high or low a few minutes before you are ready to transfer eggs or larva to the tank. It is surprising just how long it can take to match up temps between the parent’s tank and the rearing tank.

I use a rearing technique called “co-culturing�. This basically means that I am growing rotifers and clownfish in the same tank at the same time. After getting everything setup and adjusted I add enough phytoplankton to tint the water the color of the phytoplankton. Then I sieve and add enough rotifers that they are at a density of about 50-100/mL. With all but the hungriest and largest of hatches the rotifer density can be maintained at an adequate level to feed the larva with little or no addition of rotifers. However there are risks to the rewards of not having to feed rotifers multiple times a day. There are two primary concerns with this method; first is that the rotifers produce wastes that will contribute to ammonia build up in the tank, second rotifers consume oxygen a precious element in a tank with several hundred breathing larva.

Getting the fry to raise.

Chances are very good that your pair did not lay their nest on an easily removable and replaceable item in your tank. This is one of the reasons to let the first couple of batches go. If at all possible you want to get your pair to lay their nest on a removable and replaceable item. Many breeders use either a small ceramic tile (6� x 6� is ideal for most species, but maybe too small for some larger species) or a terracotta flower pot. It is important to have several tiles or pots that are as close to identical as you can get. If this is the situation you are in, try placing a tile or pot over the place that the pair laid their nest the day after the eggs hatch. With any luck the pair will accept the new spawning substrate and you will be set for future nests. It should be noted that there is a possibility that you will disrupt the pair and they may stop spawning either temporarily or permanently.

If the nest site that your pair has chosen is not easily covered by a removable substrate, try placing the tile or pot a few inches from the existing nesting site. They may just decide they like it better and switch.

Removable substrate
If you have established a removable and replaceable spawning substrate, you have just made your life and the life of the larva much easier! Simply remove the tile/pot the day that the eggs are scheduled to hatch. Place it in the prepared rearing tank and place your air stone(s) to aerate the eggs. Place the stone so that all of the eggs are gently waving in the current created by the bubbles. If you are unsure of the volume of air to use, error on the too much side. Keep the other air stone in the tank low, you do not want the newly hatched larva to be blown around the tank when they hatch. The general rule of thumb is to have enough current that keeps the water moving, but allows the larva to swim where they want to.

In tank hatches
If you have not established your pair on a removable nest site or can not convert them, you will have to go fishing. Clownfish larva are attracted to moderate light sources, but are repelled from strong lighting. You can use a dim flash light to attract the larva to it and then use a cup or small bowl to scoop the larva out and into the rearing tank. You do not want to use a nest, you will damage the very fragile larva. With that said, be gentle with your scooping too. There is a good section in Joyce Wilkerson’s book on methods for collecting larva from the brood stock tank.

Feeding the larva

For the first 1 to 8 days (depending on species) you will need to provide a dense population of fortified with phytoplankton live rotifers. You will need to maintain a density that allows for a larva not to have to move more than 1.5 body lengths to site a rotifer to eat.

3 Day old A. ocellaris larva with a full belly of rotifers

Some species of clownfish produce fairly large larva. For example the A. Ocellaris and A. Percula species both produce fairly large larva that will feed on rotifer on their first day and will be ready to move on to a larger second food source by day 4 to 6. Another example are maroon clownfish, which have fairly small larva that generally do not feed (or at least well) on rotifers until the second or third day from hatching.

As the larva develop the density of rotifers is less critical and can be reduced if need be. If you use the co-culture method mentioned before, be aware you may need to supplement the rotifer population with additions.

Do not add the rotifer culture directly into the rearing tank. Sieve them with a 53µm sieve and rinse them before adding them to the tank.

The second food for your clownfish larva can be either newly hatched BBS (baby brine shrimp) and/or crushed Cyclop-eeze. The key here is to feed the fry and not the tank. Feed them enough that most all of the food is consumed with in one to two hours. You will need to feed them a minimum of three times a day, but five is better.

12 Day old A. ocellaris feeding on Cyclop-eeze

22 day old A. ocellaris stuffed to the gills with BBS and Cyclop-eeze.

A final note

As I mentioned breeding and raising clownfish is a very long subject that is not well suited to a BBS like RC. So there are a lot of little details left out of the above. This has been intended as an introduction and informational post. If you have specific questions about the process please feel free to ask.
Old 09/11/2003, 02:04 AM
kris4647 kris4647 is offline
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Join Date: Feb 2003
Location: Seabrook, Texas
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I think this is a Sticky Carlos...

Nice Job John
All paid jobs absorb and degrade the mind.------Aristotle
Old 09/11/2003, 02:16 AM
JHardman JHardman is offline
Rare Clownfish Freak
Join Date: Jan 2003
Location: Phoenix AZ
Posts: 6,035
Originally posted by kris4647
I think this is a Sticky Carlos...

Nice Job John
Actually I intended this to be part of the clownfish FAQ that is being worked on. So no need for a sticky until the FAQ index is ready or maybe its the content needs to be ready to create the index?
Old 09/11/2003, 02:55 PM
Flanders Flanders is offline
I have no catchy title
Join Date: Nov 2002
Location: Syracuse, NY
Posts: 2,696
Wow John, you really have a knack for condensing a whole mess of information into a readable, understandable format. I've really learned a lot from you on this forum. Thanks.

I wondered why my ocellaris pair hasn't started spawning again since my tank leaked. Now I know. I have to quit messing with the tank!
Old 09/12/2003, 02:33 PM
forrest2906 forrest2906 is offline
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Join Date: Jul 2003
Location: Idaho.....Boise
Posts: 78
Great info!
Old 09/12/2003, 03:23 PM
Mimbler1 Mimbler1 is offline
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Join Date: Oct 2000
Location: Wichita, KS
Posts: 561
Thanks! I ordered a copy of Joyce's book just before reading your post - you conveyed a lot of information in a small amount of space!
Old 09/13/2003, 07:27 AM
lemmiwinks lemmiwinks is offline
Registered Member
Join Date: Jan 2003
Location: Perth, West Australia
Posts: 281
rather than calling the collection of these extremely informative threads you have been working on (good work) clownfish FAQ, try to squeeze in as much as possable about whats in the FAQ in the title (i.e clownfish FAQ - breeding, pairing, how to keep a "nemo" etc)

i can garuntee that people will still start threads on these questions that are asked so frequently (once by myself :P)

once again good work JHardman. i have learnt a bundle from this forum, with a majority of the information from yourself, as well as bonsai nut and black percella. thanks guys

Old 12/20/2003, 08:22 PM
Atticus Atticus is offline
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Send a message via Yahoo to Atticus
Did we forget this one in the Clownfish Frequently Asked Questions?
"Good enough is the enemy of excellence."
Old 12/20/2003, 09:10 PM
JHardman JHardman is offline
Rare Clownfish Freak
Join Date: Jan 2003
Location: Phoenix AZ
Posts: 6,035
Originally posted by Atticus
Did we forget this one in the Clownfish Frequently Asked Questions?
As a matter of fact, yes. Oh Carlos...
Old 12/20/2003, 09:17 PM
Carlos Carlos is offline
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Join Date: Dec 1999
Location: Melrose Park, IL
Posts: 3,187
Sorry, I was in FL for a week diving. Just got back in town.

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