Clownfish are one of the easiest marine aquarium fish to breed. Unlike many of the other marine fish, clownfish regularly spawn in a marine aquarium. Furthermore clownfish have relatively large eggs and larvae which make rearing them a somewhat easier task as the larvae are able to eat cultured foods.
There are a few very important steps to breeding clownfish. These include setting up the tank, choosing the brood stock, feeding, spawning, and raising the larvae.
Setting up the Tank
A clownfish spawning tank should be as large as possible, and preferably not smaller than 100 litres. If the purpose of the tank is to solely breed clownfish than it would be wise to avoid putting any other fish in the tank.
As a rule of thumb the more natural a tank is the more at home the fish will feel, and the more likely they will be to spawn. This doesn’t mean that a tank with a flowerpot and a thin layer of coral sand won’t produce results, it is just that the more relaxed and stress-free the fish feel, the sooner they will spawn and the healthier the eggs will be.
An ideal tank would be a 1 meter x 450mm x 450mm tank filled with a bit of live rock, a layer of coral sand at the bottom, a nice anemone, enough lighting for the anemone, and good filtration preferably consisting of an efficient protein skimmer in the sump. As the bioload of the tank would just be the clownfish, the live rock and protein skimmer would handle the ammonia and organics from the fish. Small weekly water changes must be done to keep down the nitrates.
In nature the clownfish spawning is linked to the lunar cycle. It is generally not practical to artificially stimulate the lunar cycle in the aquarium. It is important however, that the lights are connected to a timer so that the fish receive a regular daylight lighting cycle. This regular day/night cycle is all that is needed.
An anemone is generally not required to breed clownfish, however, it certainly makes the task much easier in the long run. In fact clownfish have been known to spawn on clay pots, clam shells, and even the aquarium glass in the absence of an anemone. An added benefit of having an anemone is that it may release compounds that help protect the eggs, even chemically, as with the apparent immunity that clownfish have with the anemone.
The key to your clownfish home is that it be STRESS FREE! That means good water quality, no aggressive tank mates, and an anemone.
Choosing the breeding pair
There are three basic ways to obtaining a pair of clownfish.
These include:
1) to buy a naturally mated pair captured from the wild,
2) to buy a small group of at least half a dozen fish, and then let them pair off naturally.
3) to buy two fish of greatly differing size.
Obtaining a naturally mated pair of clownfish is always the best option. This is because the pair of fish will be a naturally mated pair from the time you put them into the aquarium and will not have to go through the territorial and aggressive struggles that happen in an aquarium when fish are first introduced. Also the fish will not view each other as aggressive rivals as they are in a pair. By introducing a mated pair into the aquarium, spawning will commence much sooner than by the other two methods.
Buying a small group of clownfish, preferably from different sources, is the next best option. This is because it gives the clowns a chance to form a hierarchal structure in the tank with the two most dominant fish naturally pairing off. It also lowers the chance of the other clownfish becoming overly stressed due to aggression from the dominant fish, as the aggression is spread out over a number of individuals. This option will produce a pair but it will take longer for them to start spawning than if they were a mated pair as soon as they were added to their aquarium.
Putting two fish of differing size in together is an extreme way of obtaining a pair of fish. The reason for this is that often the larger fish will be very aggressive towards its own kind and, if there is only one other clownfish, than that aggression can cause the smaller fish to become very stressed, and more prone to disease. This problem will persist until the larger, more dominant female fish accepts the smaller male. This task may take anywhere from a few days to several weeks.
Feeding
Once the tank is set up and the fish have been introduced to the tank it’s time to start feeding them. Believe it or not feeding is probably the most important aspect of whether you will have success with breeding clownfish. If your breeding pair do not get fed a healthy diet than they generally do not to develop good quality batch of eggs. If the eggs are of bad quality, then no matter how hard you try, your success rate in raising the larvae is far less.
The key to nutrition in clownfish is a mixed diet of fresh raw seafood and vegetable matter. I have also found by using a good multivitamin which is added to the food daily also helped tremendously in a good batch of eggs.
A good diet for clownfish includes mussels, prawns, squid and green vegetables. These can be mixed together into a blocks of frozen cubes, or can be just fed separately. The amounts of food to feed the clownfish depends on their size, however, it is always best to feed small amounts at regular intervals. Remember, clownfish will take large bits of food to the anemone so it’s a good idea to feed them small bits!
Spawning
Once the clownfish have settled into their new home, anywhere from one to twelve months, spawning should start. The first indication of possible spawning is when the male clownfish swims up and down in front of the female. The male will dance in a head-up fashion and will thrust towards the female. This is known as the clownfish waggle. This behaviour is a pretty good indicator that spawning will happen soon. The next indication is when the male, and often the female, will start to clean a portion of rock near the base of the anemone. This is a good indication that spawning will start within a day or two. You generally find they lay either first thing in the morning or late afternoon. You will find a small tube protruding near the anus from both the fish this is called an ovopositor. You find the female starts laying eggs in short batches followed by the male shortly after fertilizes them. The process of laying eggs takes anywhere from 2 to 3 hours. The eggs look like little capsules about 2 to 3 mm long and 1 mm wide. If the adults have been fed well the eggs should be a bright orange colour. During this time the clownfish, particularly Amphiprion clarkii, or in other words the African clown may lay up to 600 eggs. More often than not however, the number of eggs start out small, around 200, and increases with each spawn and as the female increases in size. Once the fish have started spawning they’re likely to repeat it at intervals of around 12 to 18 days.
The eggs usually take from 6 to 10 days to hatch depending on the temperature. One day before hatching the larvae develop a silvery colour around their eyes. This is the time when you must make a decision: Either you leave the eggs in the tank to hatch, and you remove the larvae, or, one day prior to hatching you remove the live rock upon which the eggs were laid.
If the eggs are to be removed on the rock then it is important that the eggs be kept underwater at all times. The water in which the eggs are kept must have also been taken from the spawning tank as small differences in water quality may damage the eggs. Once the eggs are in the larval rearing tank then they must be provided with sufficient water current to properly oxygenate them. . The easiest way to do this is via an airstone that produces coarse bubbles. All then that is required is to remove the rock after hatching.
If the eggs are to be left in the main aquarium then some planning will have to be made. To make things easier, the lights can be turned off as the larvae hatch within 2 hours of darkness. Once the lights have switched off all circulation pumps and return pump must also be turned off. This will ensure that the larvae are not sucked up and damaged by pumps and water currents. After the pumps have been turned off and the tank is still it’s time to wait! At this stage I have found with my experience it is best to shine a torch in a narrow beam from the top. The eggs will hatch in waves, and as the larvae hatch they will swim towards the light. Once they gather together into small groups. You then can either siphon the larvae off into the larval rearing tank with airline tubing, or I find using a glass beer mug the most successful in scooping out the larvae. This is done repetitively until all larvae are caught.
Larval rearing and tanks
Clownfish larvae can be reared in many different ways. Old 2 foot aquariums or small tanks that are built to clip into the aquarium of the breeding pair can be used to start with for the first 10 days to 2 weeks. As mentioned when using a 2 foot tank for the first 10 days to 2 weeks they must be fed at least three times a day with rotifer. All excess food siphoned off with airline tubing twice a day. This is to stop the decaying of food which causes fungus and infection or pollution of water. At this stage only airstones are used and water changes are done daily.
At roughly 10 days to 2 weeks the fry are then moved into the 600 L aquarium where the setup for fry is to have a central standpipe in the tank, and to place a mesh screen of between 100 and 300 microns around it. The different mesh sizes are used for the different sized live feeds such as rotifers and artemia. Water overflows into a sump where there is some sort of both biological and mechanical filtration. A low volume pump then pumps the water back into the tank at very slow rate, just enough to cause the water to circulate slowly and keep the larvae moving. An airstone may be required in the centre of the tank along the side of the screen to ensure that it does not block up. This system closely matches the natural environment where they are found drifting in the surface waters. By moving the fry into a larger aquarium such as 600 L tank and feeding them on artaemia (brine shrimp) three times a day I found that the growth rate and deaths were far less. At three weeks old I started weaning them onto a good quality baby food fake or even something like Cyclop-eeze. I got from day of hatching to date of selling the fish size to approximately 30 mm. These fish were then is three months old.
The second option is to have a tank with only surface aeration provided. This setup is much easier to prepare but water quality can become a problem unless regular water changes are performed to reduce ammonia levels. A further problem develops in that it is much harder to flush excess live foods out of the tank.
The larval rearing tank should receive the same lighting cycle as the main tank. It preferably should have its own light and timer. is that the larvae are visual predators and require light to hunt for their live food prey.
Conclusion
Hopefully my article has given you the hobbyist a start to breeding. It certainly very challenging and exciting reward when you succeed.
