Here is some interesting info I was giving yesterday when I told ppl about my clowns spawning
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.
