🐾 Pets Alpha
🐠 Fish Species Guide

Harlequin Rasbora

The perfect beginner schooling fish — hardy, peaceful, and marked with a distinctive black triangular wedge. That copper-orange body, that jet-black "harlequin patch," those perfectly synchronized schools. Complete guide: one of the easiest fish to breed by accident, and why they're the ideal Betta tank mate.

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📋 Species Overview

Name
Trigonostigma heteromorpha
Lifespan
5 – 8 years
Size
4 – 5 cm
Min. Tank
38 L / 10 gal
Temp/pH
22-27°C / 5.5-7.5
School Size
8+ minimum

🎭 The Iconic Black Triangle — Harlequin vs Lambchop vs Espei

Harlequin Rasbora: large black triangular patch covering the rear half of the body. Lambchop Rasbora (T. espei): smaller, narrower wedge — more orange, smaller fish. Hengel's Rasbora (T. hengeli): thin black line + neon orange stripe above it. Harlequins are the largest and hardiest of the three, making them the best choice for beginners.

🥚 Easy Breeding — They Glue Eggs to Plant Leaves

Harlequins are egg-scatterers with a twist: the female glues eggs to the UNDERSIDE of broad plant leaves (Cryptocoryne, Anubias). This is unusual for cyprinids. To breed: condition with live foods, provide broad-leaved plants, use soft acidic water (pH 5.5-6.5), and raise the temperature slightly. Eggs hatch in 24-36 hours. Remove parents after spawning — they will eat the eggs.

💰 Cost

CategoryCost (USD)
🐟 $3-$6 each | 🐟 Group of 8 $24-$48 | 🏠 38L Setup $80-$200