Setting Up a Breeding Tank

How to set up a dedicated breeding tank: size, gentle filtration, spawning media, spawning triggers and protecting eggs from being eaten.

Overview

A dedicated breeding tank gives a spawning pair controlled conditions and protects the eggs and fry from being eaten. Most aquarium fish require specific spawning triggers before they will breed, and a separate tank lets these be applied without disturbing a community. Isolating the pair also removes tankmates that would otherwise consume the spawn and makes it far easier to monitor whether spawning has occurred.

Tank size and filtration

For most common aquarium fish a breeding tank of around 38-76 L (10-20 gal) is sufficient. Filtration should be gentle, such as a sponge filter or an air stone, so that the current does not injure eggs or sweep up newly hatched fry. A well-seasoned tank that has developed biofilm, algae and microfauna is preferable, because these provide natural first food once the fry become free-swimming.

Spawning media

Spawning media give eggs a place to settle out of reach of the parents. Fine-leaved plants such as java moss, plus java fern and anubias, provide natural spawning sites. Mesh barriers, egg-crate panels or floating plant baskets let eggs fall through to safety while the parents stay separated from them.

Spawning triggers

• A sudden temperature drop applied through a cooler water change.
• Adjustments to water parameters such as pH, GH and KH.
• Changes in lighting, such as dimming the lights.
• Adding spawning plants or switching the substrate, including bare-bottom setups.

Protecting the eggs

Egg-scattering species release eggs and milt among plants and do not guard them, so in a home tank the eggs are quickly eaten unless they fall out of reach. After spawning, the standard practice is to remove all adults so the eggs can develop. Some eggs hatch within about 24 hours.

After spawning

Once the adults are removed, lowering the water level reduces the energy fry spend swimming, and frequent partial water changes keep quality high. Parental-care species such as discus, which guard their eggs, can instead be left with the brood, so the setup depends on the reproductive strategy of the species. The first foods should be ready before the fry become free-swimming, since at that point they need very small live foods or fine substitutes immediately and cannot wait for a culture to be started.