Dwarf rainbowfish

Overview

The dwarf rainbowfish (Melanotaenia praecox), also sold as the neon or praecox rainbowfish, is a small, dazzling rainbowfish with a shimmering blue body and glowing red fins in males. Active, peaceful and hardy, it brings the metallic sparkle of larger rainbowfish to a more manageable size. A shoal cruising a planted tank under good light is genuinely electric.

Tank & water

Though small, they are active swimmers, so give a shoal at least 110 litres (30 gallons) with length. Priorities:

• Temperature: hold 22–28 °C with a reliable heater.
• Water: they prefer neutral to slightly hard water, pH 6.5–7.5, and are adaptable once acclimatised.
• Filtration and flow: they enjoy some current — a filter with good turnover suits them.
• Light and planting: bright light over open water with planted edges makes their blue and red shimmer.

Feeding

Dwarf rainbowfish are active omnivores with upturned mouths that feed at the surface and mid-water. Feed a quality flake or micro-pellet staple with frozen or live foods — daphnia, bloodworm, brine shrimp — and some vegetable content. Feed small amounts two or three times a day to fuel their constant swimming.

Tankmates

Peaceful and active, they suit lively but gentle communities: other small rainbowfish, harlequin rasboras, larger tetras, zebra danios and peaceful corydoras. Avoid slow, timid or nippy fish. Keep a shoal of six or more with a mix of sexes — see best centerpiece fish for a community tank.

Common mistakes to avoid

• A tank too small for their active swimming
• Keeping too few, which dulls colour and confidence
• Dim tanks and pale substrate that mute their shimmer
• Slow or nippy tankmates that clash with their pace

Give dwarf rainbowfish a bright, open, planted tank and a proper shoal, and their metallic blue-and-red flashes make a spectacular, easy centrepiece.