There is a school of thought that the best way to raise fish eggs and larvae in captivity is to strip them from the holding female (vernacular for mother) and place them in an egg tumbler. An egg tumbler is a container that gently stirs the fish eggs and larvae, which is simply a re-enactment of what occurs when they are in the holding female's mouth. This method has been statistically proven to provide fish eggs and larvae with a higher rate of survival. They are available to purchase, but why spend money when you could make your own?
Create the body of the tumbler by using a 2-liter soda bottle. Sever the bottom end of the bottle so there is a large opening.
Cut a rectangular opening in the bottle. The purpose of this opening is to serve as a filter by allowing water to exit the tumbler and into the aquarium where it will be placed.
Cover the rectangular opening with a thin, tightly woven mosquito netting. Seal the netting with an adhesive, such as glue, or preferably, silicone.
Puncture a small gap in the bottle cap so that the plastic L-shaped pipe can be inserted.
Attach the L-shaped pipe to the valve and power head. This is what causes the movement that will stir the fish eggs and larvae.
Connect a suction cup to the tumbler by puncturing a small hole not far from where the bottom end of the bottle used to be. The suction cup will prevent the tumbler from actually tumbling around the fish tank.
When purchasing a power head for this project, Find one that you can place a filter inside. If the power head does not have a filter, then it will be difficult to keep the egg tumbler sanitary.
Make sure that the mosquito netting fits smoothly over the tumbler, or else you run the risk of the fish eggs and larvae being flushed out and killed.