Clarkii Clown Fish, or Banded Clownfish, are some of the easiest salt water fish to breed and rear. Provide proper tank conditions and the fish egg hatching is generally quite predictable. But raising clown fish fry successfully to adulthood, will take some care, as outlined here by author Hennie Landman.

Article By: Hennie Landman
Edited By: Elizabeth M. Lukan

(Reprinted by Permission of Elizabeth M. Lukan, Editor of Fish n’ Chips, 5/31/02)

Fish Egg Hatching:

According to the experts, the eggs take from 6 to 15 days to hatch, depending on the temperature. My eggs hatched as regular as clockwork on the evening of the seventh day. During the last day, the eggs change from a reddish brown to a silvery colour. This is a positive indication that the eggs are due to hatch that evening.

All the power heads and external filters should be stopped the evening of the hatching. Just before the last light goes out, one should also stop the sump return pump. After lights out, one should check on the tank every 15 minutes or so, using a red filter in front of a torch (Editor’s Note: aka flashlight). About 1-2 hours after total darkness, the eggs hatch, all within a few minutes of each other. At this stage, one should switch on a dim exterior light, just to make it easier to work in the tank. Then, use a bright torch (without filter), and shine the light into the tank at a place convenient to catching the fry. All the hatched fry will immediately start to swim towards the light, and congregate in great masses just below the water surface. It’s then a simple thing to scoop them up into a shallow bowl (or even a large soup ladle). The fry should then be transferred to the rearing tank, and gently released by immersing the bowl below the water surface. Care should be taken to ensure as little current and turbulence as possible while doing this, as the newly hatched fry are very delicate.

Raising Clown Fish Fry: The first few days

In nature, the fry would swim to a depth of a several meters below the surface. Being confined to a much shallower tank, they still try to swim away from the light, and will end up “standing” on their heads on the bottom of the tank. This stress will cause them to die within the first day or two. The rearing tank should thus be kept in total darkness for the first 24-36 hours. Thereafter, the light intensity should be GRADUALLY increased over a period of four to six days, ending with the full power of one 20-30W NO fluorescent lamp. This can be achieved by covering the tank’s top with a cover glass, on which one places two portions of dark cardboard. After the initial 36 hour’s darkness, one can move the cardboard sections slightly away from each other, thus increasing the “light gap.” During this period, the fry should remain free-swimming in the center of the tank. Any tendency to “head stand” should be enough indication that the light intensity is too high.

Clown Fish Habitat: The Rearing Tank

The rearing tank should ideally be a 7-10 gallon (20-40 liter) tank. The bottom and sides should be painted a dull black, or covered with tight fitting matt black cardboard sheets. (In nature, the light only shines from above, and the fry orientate themselves accordingly. Even the slightest bit of light shining through a side panel will cause the fry to cluster around it, trying to swim through the glass. In doing this, they miss out on food, and invariably die). There should be no substrate, and the heater’s pilot light should also be covered (or painted over), else the fry will cluster around the heater.

There should be no filtration in the tank until the fry are at least 3 weeks old. Water movement in the tank should be accomplished by one or two airlines, discharging air from the bottom. During the first 3-4 days air should be pumped through the lines without using an air stone, as the small bubbles tend to “capture” the fry, and cause them to float on the water’s surface. This is a sure way to kill them.

Just allow VERY GENTLE aeration, like one or two bubbles per second!

Continued… in “Breeding Clown Fish, Part Three

Featured Image Credit: Sebastian Pena Lambarri, Unsplash