Three-spined Stickleback

The Three-spined Stickleback is one of the most scientifically studied vertebrates in the world, yet in the aquarium it remains a novelty. Males in breeding condition turn a vivid red-orange on the throat and belly, developing bright blue-green eyes, and build an elaborate nest from plant material, glued together with kidney secretions.

The male then courts females, fans the eggs, and guards the nest and newly hatched fry. This complete parental behaviour, combined with compact size and cold tolerance, makes it a fascinating species for a species biotope tank.

Sticklebacks are found in fresh and brackish water across the Northern Hemisphere and tolerate a very wide range of conditions. Diet must include live or frozen meaty foods — they do not thrive on dry food alone.

Water: 5–20°C, pH 6.5–8.0, GH 5–20; tolerates fresh and slightly brackish; well-oxygenated water essential. Tank: minimum 60 L species tank with fine sand, rooted plants, and open swimming space. Feeding: carnivore — live/frozen daphnia, cyclops, baby brine shrimp, and small bloodworm; dry food accepted reluctantly. Breeding: male builds plant nest; guards eggs and fry; remove female once eggs are laid. Compatibility: semi-aggressive; best as a species tank; will eat very small fish and shrimp.