Breeding Clownfish (Budidaya Ikan Badut)
David Bloch

Introduction

Clownfish are one of the easiest tropical marine aquarium fish to breed. Unlike many of the other tropical marine fish, clownfish regularly spawn in a marine aquarium. Furthermore clownfish have relatively large eggs and larvae which makes rearing them a somewhat easier task as the larvae are able to eat easily cultured foods

The purpose of this article is to convey the information that I have found and learned over the last few months while I have been raising clownfish. This information is a compilation of both my ideas and the ideas from other articles written about clownfish. A complete reference list of clownfish related articles will be compiled at the end of the article.

There are a few very important steps to breeding clownfish. These include setting up the tank, choosing the broodstock, feeding, spawning, and raising the larvae. These points will all be discussed in detail below.

Setting up the Tank

A clownfish spawning tank should be as large as possible, and preferably not smaller than 100 liters. 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. Small non-aggressive fish can be added, however, once the fish start spawning anything that comes toward them is viewed as a threat and is chased away.

As a rule the more natural a tank is the more at home the fish will feel, and the more likely they will be to spawn. This is not to say 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 3x2x2 feet tank filled with live rock, a layer of coral sand at the bottom, a nice anenome, bright lighting, and good filtration preferably consisting of an efficient protein skimmer. 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. A trickle filter could be used providing regular water changes are performed to keep the nitrates low enough for the anenome to do well.

In nature the clownfish spawning is linked to the lunar cycle. It is generally not paractical 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 anenome 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 anenome. An added benefit of having an anenome is that it may release compounds that help protect the eggs, even chemically, as with the apparent immunity that clownfish have with the anenome.

The key to your clownfish home is that it be STRESS FREE! That means good water quality, no aggressive tank mates, and an anenome.

Choosing the Broodstock

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 four fish, and 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. The best news however, is that 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 broodstock do not attain the correct amounts and types of nutrients than they will not be able to develop good quality eggs. If the eggs are of bad quality, then no matter how hard you try, you will not have much success in raising the larvae.

The key to nutrition in clownfish is a mixed diet of fresh raw seafood and vegetable matter. A good diet for clownfish includes mussels, prawns, squid and green vegetables. These can be mixed together into a mash anf frozen, 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 their anenome 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 will commence. 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 behavior is a pretty lose indicator but generally means that spawningwill 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 anenome. This is a good indication that spawning will commence within a day or two. The last indicator of spawning behavior is the appearance of both the male and female clownfishs’ genital tubes.

Spawning starts when the female swims over the cleared patch of rock and deposits a small line of eggs with her ovopositor. The males follows shortly after and 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 color. During this time the clownfish, notably Amphiprion clarkii, 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 15 days to hatch depending on the temperature. One day before hatching the larvae develop a silvery color 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 to and within the tank must be ceased. 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! The eggs will hatch in waves, and as the larvae hatch they will swim to the surface. Once at least a quarter of the eggs have hatched it’s time to use the torch (flashlight). The torch is shone in the water from above, and used to concentrate the larvae into a small group. Once this is done the larvae can either be siphoned into the larval rearing tank with airline tubing, or dipped out with small plastic cups/containers. This is done repetitively until all larvae are caught.

Larval Rearing Tank

Clownfish larvae can be reared in many different sorts of containers and tanks. Old 2 foot aquariums can be used, however, I have found that circular tanks give much better results.This is because square/rectangular tanks have corners, and with no strong currents to thoroughly mix the water, dead spots develop in the corners. This occurence in the end will cause the death of many clownfish larvae. With round tanks there is no such problem, as there are no corners, and it is very easy to get water to circulate in a circular fashion.

An ideal larval rearing tank is a round plastic or fiberglass tank with a water holding capacity of between 50 and 150 liters. These tanks can be set up as: 1) having a filter and recirculating water, or 2) stand alone, and just using airstones and water changes.

The ideal setup for clownfish larvae is to have a central standpipe in the round 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 pumpthen 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 center 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.

The second option is to have a round 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 the above information gives you, the hobbyist, a concrete start to breeding clownfish. It can be a very challenging, yet exciting venture, particularly when you are rewarded with post-larval juveniles. It is then when you can sit back and murmur “success”.

David Bloch

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