Breeder box, net or grow-out tank
- A breeder box hangs inside the main tank and shares its water and heat. It suits a handful of livebearer fry for their first weeks, but water moves through it slowly, so uneaten food fouls it fast. Clean it daily.
- A breeder net lets more water through than a box, so it stays cleaner, but fry can be sucked against the mesh near a strong current.
- A grow-out tank, a bare 10 or 20 gallon with a heater and a sponge filter, is the best home for more than a dozen fry or for egg-layers. A sponge filter will not suck them in, and a bare bottom makes leftover food easy to siphon.
- Dense plants or moss in the main tank save some livebearer fry without any of the above, if fewer survive is fine.
Clean water every day or two
Fry eat often and are small, so their water fouls faster than the main tank’s and they suffer from it sooner. Change 10 to 20 percent every day or two, with water at the same temperature, and siphon leftover food off the bottom with airline tubing so fry are not sucked up. Run the grow-out filter in the main tank for a few weeks before you need it, so it is already cycled.
Food as they grow
Start with food small enough for their mouths: infusoria or liquid fry food for the tiniest egg-layer fry, then microworms and baby brine shrimp, then crushed flakes as they grow. Feed small amounts three to five times a day; fry fed well grow much faster than fry fed once a day. Feeding fry · Hatching brine shrimp
When they can join the main tank
Move the fry once they are too large for any fish in the main tank to swallow, usually after four to eight weeks, depending on the species and how well they were fed. Float them in a container to match the temperature first, as with new fish. Acclimating fish
Livebearers and convicts can fill a tank within months. Before a batch grows up, ask your local fish store or a fish club whether they take them, and keep males and females apart if you have nowhere for more.