My clownfish laying eggs.
In order to breed clownfish, you will need a mated pair. The easiest way to do this is to purchase a pair. Often times fish stores can order a mated pair or many online shops carry them as well. The second way you can be sure you have a mated pair is buy two clownfish when they are young. When clownfish are young, they are always males. Once they have determined the dominant fish, it will change sexes into a female. After some time, you will be be able to tell which is the female because it will always be larger. This comes after much fighting between the two fish.
Often times the female will nip at the males tail and the male will look like he is having a seizure. He will roll on his side and start twitching rapidly. This is his way of saying I give up to the dominant female. My fish took 6-8 months before the sex change was obvious. Any species of clownfish will work. I breed true perculas in my 150 gallon tank. Once they start breeding they will lay eggs every 12-18 days. 
A tank of at least 30 gallons is needed to keep clownfish happy. Clownfish are not as sensitive as some other marine fish but keeping the water clean does make them more likely to spawn. Be sure to make weekly water changes of at least 10% of the total water volume. A good protein skimmer can make water changes less frequent. The other tank mates (if any) must be peaceful. Beware of putting different species of clownfish together. They often will fight and stress each other out. Stressed fish will not lay eggs. Having an anemone helps to make the clownfish feel comfortable to lay eggs. However, an anemone is not required. A good amount of live rock with plenty of hiding places will make the fish feel more comfortable. The lighting for the tank should be on a timer. A timer will get the fish in the routine of sunlight and darkness. Try to feed the fish at the same time everyday with a good mix of different kinds of frozen and flake food. If the fish are not getting the proper vitamins and nutrients, whatever eggs they do lay will most likely be of poor quality.
Once the fish have become acclimated and are on a regular schedule they will begin to act differently around spawning time. You will notice that the female suddenly gets thicker in the middle of her body. This could be an indication of a pregnant clownfish. You also might notice that the fish are constantly cleaning off a rock with their mouths and fins. This is to get the site clean for the eggs. When the day to lay eggs does come, you will notice a small tube sticking out of both the male and the female. On perculas it is in the center of their middle white stripe. This tube is where the eggs and sperm will come out of. First the female will swim back and forth on the clean part of the rock depositing eggs. When the male gets his turn he also will swim over the eggs to deposit sperm to fertilize the eggs. For close to an hour the fish will swim back and forth over the rock depositing eggs and sperm and constantly airating them with their mouths. If you missed the laying of the eggs, they will be stuck to the rock the fish have prepared and appear as an orangish color. The male cares for the eggs and will constantly swim back to the eggs and wave his fins on them to keep them aerated. You might also see him blowing on them or picking off the eggs that are dead. The clownfish will be very territorial about the eggs. Any fish that comes too close, regardless of size will be chased away or nipped at. This also goes for hands in the tank.
Happy, healthy, and comfortable fish will be more likely to lay eggs. Be patient with your clownfish and one day when you are least expecting it, your fish will begin to spawn. It can be a rewarding experience if the proper steps are followed.
hey,
i have a marine aquarium and i am only 12. i hope to buy a mating pair of clowns soon and hope that i will have the capability to bring them up. i would like to thank the creator/s of this website for giving me this valuable information. so thanks guys, keep it up!
Best of luck to you. Let me know in the forum if you need any more help. http://www.breedclownfish.com/forum
–Scott
what do you do with they eggs after? someone said you should take them out and put them in another tank so the corals won’t eat them?