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 Tips on Breeding Clownfish

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Clownfish or anemonefish are among the easiest marine fish to breed and come highly recommended as a good place to start if you are interested in breeding marine fish. This is not to say it is an easy process but considering the captive breeding of most marine fish is not yet possible, even in laboratories, it is by comparison an easier place to begin.

 

This article deals specifically with ampipherion ocellaris or the false percula. Methods and timings may vary depending on the species but the same general process can be applied to many types of clownfish. Check the further reading section for more information on other species.

 

The Parents

An obvious starting point, it takes two to tango as they say. A proven breeding pair is preferable but are highly sought after, most LFS will stock pairs of clowns but often they are still too immature to breed (size is not really a good indicator) and they may not have been a pair for long. Be very careful you are getting what you pay for, I have heard rumours of unscrupulous breeders subjecting fish to copper baths to sterilize them thereby making them unable to be bred by others, only buy from reputable sources.

 

Clownfish have 3 stages of sexual development, at metamorphasis (from larvae to fish) they are all juvenile males, soon after metamorphasis the most dominant and the largest will develop into a female, the next down the list in size and dominance will become a fully fledged male whilst the remainder will stay juvenile males. This is the hierarchy of the clownfish family, if the female should die then the male becomes the female and the next juvenile male in line steps up to be the next male so on and so forth. Once a clownfish has developed into a female it cannot go back to being a male, the change is irreversible.

Because of this we can successfully pair fish together but you need to know the origins of the fish, any clownfish which has spent much time on its own will develop into a female, the tricky bit is finding the male. This is why most pairs available for purchase are too young to successfully breed straight away, smaller juvenile males are used to pair up with known female fish to get compatible pairs. When the juvenile is added to the female there is often a bit of aggressive behavior from the female but if the male is resilient enough to ride out this initial period then the fighting should subside and the result is a matched pair of clownfish capable of breeding.

 

Any pair of clowns (wild caught or tank bred) will take some time to settle into their new home before they start breeding, this can take anywhere from 2 months up to a number of years so patience is important here. The environment and feeding are the two most important elements. The breeding tank must be free of predators (preferably free of all other fish), your clowns must feel comfortable and safe to be able to breed. Because of this it is also important the tank is not in a high traffic area, fish can be easily startled by kids, televisions, stereos etc. An acceptable surface for the eggs to be laid is essential, in the wild clownfish lay their eggs on rock at the base of their host anemone, in a captive tank an anemone is not required for the breeding process and a clay plant pot is often recommended as an ideal refuge and laying surface. Donít be stingy, use a brand new pot, a pot which has had plants in it can leech chemicals from fertilizers into your water which can be deadly to fish, no matter how hard you scrub the pot.

The other important factor is lighting, whilst strong lighting is not essential for fish a regular lighting cycle is required if you want your clowns to breed. You donít need to go to the extremes of duplicating the lunar cycle but a 12hr on, 12hr off daily cycle is advisable and use timers for your lights, the time the lights go on and off each day must be consistent and is more important than the duration time.

 

The other element considered important is the quality of food given to the parents. A good balance of fresh frozen, flake and live foods is suggested. Mysis shrimp or even baby brine can add good nutritional value. The more nutritionally sound the parents diet is the healthier and stronger the eggs will be when laid. Keep them well fed and regularly.

 

Larvae Rearing Tank

Newly hatched clownfish require a separate tank in which to develop into adult clowns, this is the larvae-rearing tank, the food which we will feed these larvae would foul a complete reef tank in less than 24hrs not to mention any pumps will suck in larvae and kill them so we need to ensure the larvae tank is 100% stand-alone. There are some good examples on the web of various designs but in my experience the simplest solutions were the best.

 


I found a 30L rectangular tank did the best job, you must ensure you have a white bottom (polystyrene underneath the tank will achieve this) as this makes the larvae easier to see. The larvae at this stage can only have light from directly above, all sides of the tank must be blocked out, I found the easiest way to achieve this was to make an elasticized skirt for the tank which could be stretched around it, blocking off all sideways light, this way once your larvae have developed into fish you can remove the skirt. Your larvae tank will only need to be filled halfway so the skirt will only need to be halfway up the tank. You will need a heater, any kind of light will attract them so when you add your heater make sure you tape over the indicator light with some pvc insulation tape, larvae can be attracted to these lights and then cook from being too close to the heater. You will also need a reliable thermometer along with some water movement and a way to oxygenate the water, an air pump will provide both of these. An air stone is not required, just set the pump to let bubbles out at a steady boil (about 3 bubbles per second).

 

On the night of hatching is the best time to fill up your larvae tank, you will reduce your mortality rate by siphoning water from the parent tank on the night of the hatch, this is then less stressful on the larvae during the change. However you need to ensure before hand that your heater is set correctly to maintain an identical temp to the parent tank so it is advisable to fill the tank up with water prior to the hatch and leave it running for a few days and adjust the heater appropriately, then turn the heater off and drain the tank so that on the night of the hatch you can just fill the tank and turn the heater on.

 

Laying

Once your clownfish begin laying we can proceed onto the next phase. Generally as it can take so long for them to actually start breeding it usually comes as a surprise to the aquarist. Letís face it no one wants to be maintaining rotifer and nannochloropsis cultures and a larvae tank for 2 years whilst waiting for that special moment. Some early indicators that your clowns are going to lay are that the male will begin cleaning the laying area meticulously whilst the female inspects the work done occasionally and sometimes will do some cleaning herself as if unsatisfied with the job the male is doing, this can go on for some time and does not always result in them laying in the immediate future. The only real true sign they are going to lay is on the day of the laying, the female extends her ovulation tube, and this can be seen extended from her body near the anus just prior to her laying the eggs.

 


Clownfish eggs one day after laying.


Laying begins generally 4-5hrs before lights out (in the afternoon according to the fish), the process can take a couple of hours depending on the size of the clutch and involves the female rubbing her underside along the rock leaving behind her a trail of eggs. She will make a couple of passes like this and then moves aside for the male to follow the same path and fertilise the eggs, then the male moves aside and the female starts again. Usually when a pair first lay, the size of the clutch is smaller (as little as 50) but this generally increases each time they lay and are reported to get as large as 1000, this authorís experience has seen at least 500 eggs laid by a mature pair. If all is well the eggs should be a bright orange colour. Yellow, green or clear eggs are usually a sign of poor nutrition, look to the diet of the parents, these eggs will probably not survive to hatching and as they become unviable the male will remove them.

 

After the eggs are laid the male then takes over housekeeping duties and rarely ventures far away from them until they hatch. His main job is to fan the eggs with his fins, this increases the oxygen flow around the eggs which is vital to their health and also keeps them free of detritus and other foreign objects. The female takes on guard duty and essentially protects the male whilst he is protecting the eggs, she tends to become very territorial during this time and will fight off anything which strays too close.

 

Hatching

There are two methods used to hatch the eggs and collect the larvae, which one you use is dependant on whether you can remove the surface on which the eggs have been laid or not. Method one is for eggs which cannot be removed from the parent tank prior to hatching, method two is for eggs which can be relocated prior to hatching.

 

About a week after being laid the eggs will develop a silvery sheen to them, by this time you will be able to clearly see the larvaeís eyes through the egg sac. When the eggs look completely silver they will probably hatch that night anywhere from 45min after lights out.

 

Method 1

You can let the lighting run itís natural cycle and stay up late to retrieve the larvae or you can turn them off a couple of hours early that night, by this stage it doesnít matter. Make sure all pumps, skimmers and powerheads in the parent tank are turned off and that the light on your heater has been taped over (the larvae are attracted to light and will fry if they get too close to the heater) and then leave the room for 45min, the room must be in complete darkness, no moonlights, nothing.

 

When you return to the room place a small penlight torch at one corner of the tank, try not to shine the light on the eggs as this will stop the hatching process for the night, leave the room for another ten minutes and if hatching has begun you should be able to see larvae swimming around the torchlight when you return. You can then begin to transfer them into your larvae tank. You can either scoop them into a cup or ladle and transfer them into your larvae tank or you can siphon them using airline tubing, apparently the mortality rate of larvae is less if you scoop but it takes hours. I siphon and lose very few as a result. If after 2hrs they have not hatched then you can usually assume they will not hatch until the following night. Donít forget to turn all the pumps back on.

 

Method 2

This method is by far the easiest if you are able to do it, on hatch night remove the eggs along with the surface on which they were laid (rock, plant pot) and place them in the larvae tank, then connect an airtube so that it blows a constant stream of bubbles over the eggs, this will keep them oxygenated much the same as the male does by fanning his fins, turn off all the lights and then leave the room. After an hour or two your eggs should have hatched and the laying surface can be returned to the parent tank. If the eggs do not hatch they should be returned to the parent tank for the male to look after until the following night.

 

Now you have hatched larvae in your rearing tank, you must cover it with something to block out the light (100% blockout for the first night) and then leave them to settle in to their new home. Prior to putting the larvae in the tank I also add some green water to the larvae tank, not too much just enough to give a tinge of colour, this will help diffuse some of the light over the first few days so as not to shock the larvae too much but will also aid your rotifer feeding.

 

Raising

Up until this point it really has all been down to the fish, you think you are a participant from the beginning but really you havenít done anything yet except provide an environment which exists without any maintenance or intervention in the ocean. Get used to it, it only gets worse from here.

In the ocean the little clownfish larvae swim off into the crevices of the reef and feed on small planktonic organisms and grow up to be clownfish. In a rearing tank we have to work hard to provide the requirements of growing larvae, at this stage it really is all up to you. You will sustain a large amount of casualties over the first few days it is inevitable.

The feeding requirements are really a 2-stage process combining Rotifers and Baby Brine Shrimp. Methods vary but I feed rotifers for the first 5 days and then BBS from there on but the time at which they can eat BBS is really dependent on the size of the larvae, smaller larvae means longer on rotifers.

 

Now at this stage I am going to assume you have cultures of green water, rotifers and brine shrimp at the ready, having already added green water to your larvae tank on the night of the hatch you now need to feed your larvae with rotifers, there are conflicting reports on how long a larvae can sustain itself without food, I have observed larvae reach 5 days without feeding (but this is the exception to the rule) but the general rule is that the next day after the hatch is the time to start feeding.

 

The feeding amount and frequency is also a very challenging area to master and will take some time, it is hard to estimate your rotifer density without looking at a sample of water through a microscope. I used to feed twice daily, morning and late afternoon (before & after work), I found keeping the larvae tank fed lightly with green water meant the rotifers continued to multiply in the larvae tank during the day so I could get away with 2 feeds, most literature recommends 4 feeds daily. Each feed I would draw a litre jug from my rotifer culture and strain it through a 20-micron plankton mesh, then I would just take the mesh and drop it face (rotifer side) down onto the surface of the larvae tank, swish it about a bit and then remove the mesh. It is important that you do this and arenít tempted just to add the rotifers and water in at the same time, as the rotifers multiply, feed and defecate in the water it becomes high in ammonia, this doesnít bother the rotifers too much but will kill your larvae very quickly.

 

The other part of your daily regime is to clean the tank, this is also preferably done twice daily and is best done just before feeding. You need to remove any larvae that have died to ensure they do not cause an ammonia spike in the tank therefore killing all other larvae, this is a very important task especially for the first 3 or 4 days. The best way I found to do this was with a piece of air tubing siphon the dead larvae into a bucket, because of the larvaeís sensitivity to light you can place egg crate and shade cloth over one end of the rectangular tank, wait a few minutes and all the larvae will swim over to the shaded spot, this allows you to vacuum the open half clean without much danger of sucking up live larvae, then just switch the shaded areas around and repeat. Conduct a 10% water change on the larvae tank this way each time you clean and the water should stay at a quality high enough for your larvae to develop.

 

By the time you get to around day five after hatching then you can start introducing baby brine shrimp into the diet, only the largest larvae will be able to feed on these at this stage so it is advisable to continue feeding rotifers until at least day 7 (maybe longer depending on the size of your larvae), it is at this stage that you must be careful of not overfeeding, be wary of adding more brine shrimp if the larvae tank still has plenty already. At this stage you should not be losing many larvae and should be able to reduce your water changes to 10% daily.

 

Continue like this until day 10, it is around this time that the largest larvae will begin metamorphosis, this is a very dangerous time for your larvae and it is suggested that you cease water changes from day 10 until metamorphosis is complete, by this stage daily water pollution should be at a minimum anyway.

 


Recently metamorphosised clownfish larvae.


Once the larvae have completed metamorphosis they will stop darting around and will develop that traditional clownfish waggle, they will also begin to develop stripes and have an orange colouring to them. Once they reach this point then the danger period is really over, they can be transferred into a pre-cycled tank for raising to adult, remember at this stage they are still too small to go into a tank with any type of underwater pump or powerhead, their tank will still need to have an air tube bubbling for oxygenation and circulation. You can then continue feeding them with baby brine but make sure you introduce both flake food and some frozen variety (mysis shrimp) as brine are not sufficient as a sole diet. I grind my flake up really fine using a mortar and pestle which can be purchased from the supermarket.
 

 

 
Reefing The Australian Way
Australian reefing forum, excellent resource.


Reefpedia
RTAW site, a searchable wki knowledgebase.
 

 

Oceanarium

Licensed WA collector, Pete & Leanne run an excellent business with a real focus on sustainable collection and propagation.
 

 

Reefculture

Great online source for equipment, supply food cultures.
 

 

ATJ's Marine Aquarium Site
Very comprehensive site, reliable source for accurate well-researched information.
 

 

Oz Reef

Great resource site with a comprehensive DIY section.
 

 

Reef Online

Another recommended online shop for marine products. 
 

 

Age Of Aquariums

Very good source for low budget pumps and equipment.
 

 

GARF (Coral Propogation)

The ultimate resource for coral propagation, a seemingly endless supply of articles on coral propagation showing step-by-step from fragging to grow-out.

All content & pictures Copyright © Steve Strachan 2006, no pictures or content to be used without the authors permission.

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