How to breed forktail blue-eyes

Forktail blue-eyes (Pseudomugil furcatus) are among the easier rainbowfish to breed. A well-fed group will spawn almost every day. The challenge is raising the tiny fry. Here's how to go from spawning to grown-out juveniles.

1. Condition the breeders

Start with healthy adults: 1 male to 2–3 females works well. Feed them several times a day for a week or two, with plenty of live or frozen foods such as baby brine shrimp, daphnia, and cyclops. Well-conditioned females fill out visibly, and males color up and display hard.

2. Give them somewhere to spawn

Forktails scatter eggs among fine plants. Each egg has sticky threads that attach to whatever it touches. You can use dense plants like Java moss or floating plant roots, but most breeders use yarn spawning mops because eggs are easy to find and pick off. Hang one mop near the surface and set one on the bottom.

Keep the temperature around 77–80 °F (25–27 °C). Spawning usually happens through the day, with most of it in the morning.

3. Collect the eggs

Adults will eat eggs and fry, so check the mops every day or two. Gently pick the eggs off (they're firm enough to roll between your fingers) or move the whole mop. Put the eggs in a small hatching container with water from the breeding tank. Many breeders add a drop of methylene blue or an Indian almond leaf to reduce fungus. Remove any eggs that turn white.

4. Hatching

Eggs hatch in roughly 10–20 days, depending on temperature. Warmer water hatches them sooner. Newly hatched fry are very small and swim at the surface right away.

5. Raising the fry

• First week: a powdered fry food (what we use), or infusoria, paramecium, or green water. Feed small amounts several times a day.
• After about a week: add microworms, vinegar eels, and freshly hatched baby brine shrimp as the fry grow big enough to eat them. Live baby brine shrimp is the staple we raise ours on.
• Water quality: fry are sensitive. Do small, frequent water changes with matched temperature, and use a gentle sponge filter or none at all with careful maintenance.

Growth is steady. Young fish start to show adult color after a few months.

Common problems

My fish aren't spawning.

Check the conditioning diet first: more live and frozen food usually fixes it. Make sure you have mature females and that the water temperature is in the upper 70s °F.

Eggs keep fungusing.

Unfertilized eggs fungus first and spread it to healthy eggs. Remove white eggs daily, keep the hatching container clean, and consider a mild antifungal like methylene blue.

Fry die after a few days.

This is usually starvation: the fry are too small for the food offered. Use infusoria or green water for the first week and feed often.

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