Breeding Clownfish by Gideon Griebenow
The (family of fish that are called) Clownfish are probably the world's favourite marine fish species. When it comes to breeding, they are also the most frequently and most easily bred marine fish (their eggs are quite large and the fry are more easily fed). That being said, it still is quite an accomplishment to get clowns to spawn, the eggs to hatch and the fry to survive.
Most marine fish are much harder to breed than most freshwater fish. Luckily, the pioneers of marine fish breeding have been gathering practical experience regarding Clownfish breeding for years now, and a newcomer can piggy-back on this collected knowledge to achieve success relatively easily.
I'm not talking Barry White on the stereo, here. Before a captive fish can breed, you have to supply it with all it needs to at least survive, and most likely thrive. I am not going to go into general aquarium health and fitness issues here. The bottom line is you need an aquarium with proper conditions. Go get it.
Then you have the specific needs for breeding Clownfish. They have to be fed a variety of good quality food, in order for them to obtain all the nutrients they need for reproducing. Read up on frozen food, live cultured food, flakes, etc. and put together a feeding schedule that fit your time, your pocket and, most importantly, the fish's needs. Along with a regular feeding schedule, Clowns will feel more comfortable having a regular light cycle. Acquire some timers for your lights and, if possible, provide them with a dawn and dusk period. While the fish themselves only need some light for sight, your lighting needs will probably be determined by other factors, such as your own viewing pleasure or other marine life. Either way, keep the chosen light cycle regular.
Another requirement for comfortable Clowns is they have to share the aquarium with proper tank mates. If fish have to use all their energy to defend themselves and their territory, they will not have much energy and time left to breed. For this reason, Clowns are often given their own breeding tank. If you do not want to set up a separate Clownfish breeding tank, you will have to limit your livestock choices to some degree. However, this does not mean you will only have one or two species to choose from. Just research each potential species thoroughly for clown breeding compatibility.
Finally, unlike in the wonderful, wide world of the wild, Clowns do not need a host Anemone to survive or breed in captivity. Actually, they are probably just as happy without one, as long as they are not threatened by other livestock. Anemones have their own special requirements, so, if you want to keep your Clowns with a host Anemone (which does add a lot of aesthetical value), make sure you satisfy its needs. Also make sure you get a compatible Clown-Anemone combination.
Choosing a Clown
While this article talks about Clowns in general, every species may differ to some degree regarding one or more of the aspects discussed. I recommend that you research the specific Clownfish species that interests you in detail.
Some Clown species are less suited than others as beginner breeding species, for a variety of reasons. For instance, Maroon Clowns can be very aggressive and difficult to pair. Some Clowns score high in one department (e.g. getting them to spawn), but lower in other departments (e.g. raising the fry). Percula and Tomato Clowns are two of the easier Clowns to breed. Identify a species that you like, make sure you know the pro's and con's of the specific species, and make sure you are willing and able to commit to the implications. I have chosen Tomato Clowns, so this article will probably be slightly biased towards them.
Clowns have a very peculiar system of sexual development. A batch of juveniles will "sort each other out" to determine the group hierarchy. The "Alpha Clown" will change into a female, the "Second in Command" will change into a male, and the rest will stay genderless. If, for whatever reason, the female disappears, the current male will change into a female and one of the genderless Clowns will change into a male. When the male disappears, one of the genderless Clowns will change into a male.
The best way to obtain a pair is probably to get a batch of 4 to 6 juveniles and let them decide it for themselves. The genderless Clowns can be removed once a female and male are identified. When you already have one Clown that has been on its own for a while, it would almost certainly be a female. In this case you could add a small Clown, that has always been in an aquarium with larger Clowns (and therefore still genderless), to your aquarium. The female will harass the newcomer in order to assert her dominance for a few days. She will chase the newcomer around and nip at it. If it knows what is good for it, it will retreat and hide, and sometimes wriggle and shake when attacked to show submissiveness. This is a very crucial stretch of time, as the female could inflict excessive harm to the newcomer, and even kill it. If the newcomer is submissive enough, and the female decides to accept it as a mate, she will stop harassing it, except for minor harmless chases to re-assert her dominance. A sure sign of acceptance is when the pair shares a sleeping spot at night, for instance a host Anemone. "It" will turn into "him", and the pair bonding will start.
Once a pair is established, the bonding of the pair will start. This could take an agonisingly long time. Of course, both Clowns have to reach maturity first before being able to breed. In addition, they have to feel comfortable with each other and their surroundings before being willing to breed. A bonding time of a year before breeding is not uncommon, even in agreeable circumstances. You have to be patient and diligent in supplying them with favourable conditions (see Ambience).
Clowns generally prefer a flat, semi-vertical surface, within about 15cm of their sleeping site, for lying their eggs on, and once they have chosen a site, they are bound to stick (excuse the pun) to it. Although not as aesthetically pleasing, a tilted tile (about 15cm by 20cm) is a perfect spawning spot. This also allows you to remove the eggs just before they hatch, and replace the tile with a similar tile in order to not disrupt the setting. Replacing a tile is much easier and less disruptive than having to redecorate for want of removing that huge boulder they have chosen to lay their eggs on. Before spawning, the pair (especially the male) will clean the potential breeding site by picking all the dirt, algae, etc. off of it. The female will get fat with eggs, and an ovipositor (tube) will become visible about a day before spawning. When they are ready, the female will attach the eggs to the spawning site by means of a very precise and recognisable style of swimming. The male will swim over the eggs and fertilise them. This process takes a few hours. From then on it is the task of (mainly) the male to care for the eggs. He oxygenates them by fanning them with his tail, and keep predators away. The eggs are mostly some shade of orange or pink (white eggs are a sign of unfertilised or rotten eggs). After a few days, silver specks appear in the eggs. These are the eyes of the little embryos. The parents may pick at the eggs, presumably to remove any unfertilised or rotten eggs. Also, remember that, as with most fish, the first spawning is usually unsuccessful, i.e. the eggs will probably get eaten by the parents. But, do not worry about this - once they have spawned, they will most probably spawn regularly (about every two weeks), and they will get better at it.
Feeding the Fry
Getting the fry to survive is probably the hardest part of breeding Clowns (and any marine fish). The main problem is that the fry are too small to be able to eat regularly available foods. But let us start at the beginning.
The eggs will hatch an hour or so after lights-out. The trick is to remove the eggs on the day just before they hatch. This can be determined by closely watching the eggs and matching it to the spawning cycle/times of the specific species. The eggs must then be placed in a separate, smaller (50 to 150 litres) aquarium (with the same water parameters of the main tank, of course) where they can hatch in safety and easily be fed. You need to feed them up to four or five times a day, and perform regular water changes because of the huge bio load (with all the feeding) and little water volume.
For the first day or two, they will live off of their egg sacks. You will be able to see when this sack is depleted. Now it is time for their first rations. Since the fry are so extremely small, regular crushed flakes or the like (as well as most commercially available products) are too big for them to swallow. What is more, they will only "hunt" moving/swimming (and thus live) food. Therefore, they need to be fed rotifers. Rotifers can be cultured on a continuous basis, but you would probably need to culture micro-algae too, to feed the rotifers. It is also a good idea to enrich the rotifers prior to feeding them to the Clowns. This is probably the most tedious part of breeding Clowns. Information on building such culture stations are readily available online and in books.
After a week or two, the fry can be fed on newly hatched brine shrimp, which are much easier to obtain and hatch. Brine shrimp should also be enriched, since they do not really contain much nutritional value on their own.
After about 8-15 days the fry will start to show colour, going through the metamorphosis quite quickly (Tomato Clown fry are especially fast-growing). You may then start feeding them more readily available food, along with brine shrimp. There is reportedly a die-off period around this metamorphosis stage, but most of the fry that survive past that point are home free!
Buy a Book
I have done quite a lot of research on breeding Clownfish over the past year or so, using various online resources and a few books. While I undoubtedly learned all I have written here from those sources (and a bit of practical experience), I wrote this article entirely from memory. I note this for two reasons: Firstly, I wanted to be sure of not plagiarising anybody by copying their words exactly. Secondly, it means that this article will provide you with (at least) basic information on the aspects you should keep in mind when attempting to breed Clownfish. While, for a few aspects, it will not be necessary to do any further research to achieve success, most of the points brought up here needs to be given special consideration as your breeding attempt progresses. If you are really interested in breeding Clownfish, I urge you to take what you have learned from this article and research on it further. Two (of many) great starting points for further research are:
Joyce Wilkerson's book "Clownfishes"