Forktail blue-eye

Overview

The forktail blue-eye (Pseudomugil furcatus) is a small relative of the rainbowfish that barely reaches 2 in (5 cm). It has a translucent yellowish body, a bright sky-blue ring around the eye and vivid yellow fins edged in black, with a forked tail. Males carry larger, more colorful dorsal and anal fins.

It comes from clear, well-vegetated streams in eastern Papua New Guinea. People love its color, the males' nonstop courtship as they flare their fins at females, and the fact that it's a peaceful fish ideal for small and mid-size planted tanks. Its weak point is a short lifespan, usually 2-3 years.

Care and tank setup

A group fits in a 15-gallon (60 L) tank with a 24 in (60 cm) front, though it looks better in 20-25 gallons. It prefers clean, stable water with a neutral to slightly alkaline pH and moderate hardness. It doesn't cope well with nitrate buildup or sudden swings, so stick to small, regular water changes.

• Keep 8 or more, with more females than males.
• Lots of plants, some floaters and open space near the top, where it spends most of its time.
• Gentle to moderate flow and a tight lid: it jumps.

It's very peaceful and a bit shy, so pair it with small, calm fish such as rasboras, dwarf tetras, pygmy corydoras, otocinclus or honey gouramis, plus shrimp. Avoid nervous barbs and large fish. A classic mistake is adding stressed store fish to a brand-new tank.

Feeding

It feeds at the surface and in midwater. Offer small foods: quality micro-pellets or crushed flakes, plus frequent live or frozen brine shrimp, daphnia, cyclops or moina, which boost color and activity. Several small feedings a day work best. It rarely forages on the bottom, so anything that sinks goes to corydoras or shrimp.

Breeding

It breeds readily: males court every day and females lay a few large, sticky eggs on moss, floating-plant roots or a yarn mop. Adults eat them, so most keepers collect the mop and hatch the eggs separately. They hatch in 10-20 days, and fry take infusoria and liquid fry food right away, then baby brine shrimp soon after. Raising a few generations offsets its short life.

Compatible tank mates

Species from our database that share water parameters, size and temperament with the Forktail blue-eye. Calculated from the data in each profile.

Check the compatibility of your whole tank →

What not to keep it with

Popular species you shouldn’t house with the Forktail blue-eye, and why.

• Common goldfish: incompatible temperatures, one may eat the other due to size
• Angelfish: one may eat the other due to size
• Clown loach: one may eat the other due to size
• Oscar: one may eat the other due to size, incompatible temperaments

Recommended equipment

What you need to keep the Forktail blue-eye healthy, checked against Amazon stock.