Healthy zebrafish will breed approximately 1/2 hour after daylight. You can breed fish for several days in a row then rest them for 7 days.

Fish can be bred in their home tank or they can be moved into a separate smaller, clean tank the night before. A quart to a 1/2 gallon container is sufficient for several pairs of fish. All containers should be square or rectangular in shape. Zebrafish seem to like corners.

Sterile marbles (see Marble Sterilization) can be placed on the bottom of the tank to keep the adult zebrafish from eating the eggs. The marbles should be in a single layer, just enough to cover the entire tank floor, leaving no spaces between them. This is to ensure that the eggs can fall to the bottom of the tank and remain out of reach of their greedy, cannibalistic parents.

The eggs can be easily collected via siphon from the marbles. Assemble a funnel lined with 1/8" to 3/16" plastic or stainless steel mesh. (This can be found in most hardware stores.) Place siphon gently under the marbles at the bottom of the tank. Start the siphon flow by mouth suction, allowing the tubing to drain into the funnel. Slowly vacuum the bottom of the tank. Be careful not to stir up the eggs, as the parents will be eagerly waiting to devour them. When the entire tank bottom has been vacuumed, refill the tank with fresh system water.

An alternative option to using marbles is to place fish into tapered tubs, placing one tub with a mesh bottom large enough to allow the eggs to fall through into a second tub. You can then easily capture the eggs in the second tub below. The mesh should be stainless steel or plastic.

Marble Sterilization

  • Rinse marbles to remove slime residue they attained from the tank (algae, etc.)

  • Place about one quart of marbles and 1/4 cup of chlorine bleach in a 1 quart container.

  • Add hot water to just cover the marbles.

  • Let stand at least 1 hour.

  • Rinse for 1/2 hour in churning system water and the marbles are ready for use.

Note: Marbles can also be autoclaved, but the former method is less expensive.