Pearl Danio

The pearl danio is a close relative of the zebra danio and just as hardy, but more elegant in appearance. Its slender, elongated body is covered with a nacreous sheen that gives off blue, purple and pink reflections depending on the angle of the light. On the rear half of the body there is a thin orange-red line running towards the tail; this line is brighter in males.

It grows to about 6 cm. It is a very fast species that is constantly on the move; since it adapts to a wide range of water values and to cool water, it is also suitable for beginners. Its shimmer is best seen in light coming from the side as the school swims.

• Gold pearl danio: a cultivated form with a yellowish-gold base color and a fainter nacreous sheen; its care is the same as the wild form.

It is spread over a wide area of Southeast Asia: clear streams in hilly regions, gravelly river tributaries and lowland ponds. The water is usually flowing, rich in oxygen and close to neutral; the temperature varies markedly with the seasons.

• Volume: at least 80 liters for a school of 6–8; a length of 70–80 cm or more matters more than volume.
• Water: 20–25°C, pH 6.5–7.5. In homes with a stable room temperature it can be kept without a heater.
• Flow: it likes moderate current; it swims in the filter outflow.
• Layout: plants along the sides, wide open space at the front and top.
• Lid: an excellent jumper; a lid is essential.

Omnivorous with a good appetite. Use flakes and granules as the staple; vary the diet with frozen brine shrimp, daphnia, mosquito larvae and bloodworms. In the wild it catches insects that fall onto the surface; it takes most of its food from the surface.

Peaceful but very active. As a school it constantly moves through the upper layer; males chase the females and each other. Because of its speed it can bother slow and long-finned species.

Good companions: other danios, medium-sized rasboras, barbs, corydoras, loaches, kuhli loaches, rainbowfish.

Avoid: slow and shy species, fish with flowing fins such as bettas, predators large enough to swallow it.

At least 6, ideally 10 or more individuals. In a large school the chasing is spread among many individuals and the fish look calmer. Kept in small numbers, a dominant male can constantly wear out the others.

It scatters its eggs among plants or gravel; there is no parental care and the eggs are eaten quickly. For breeding, an egg grid, coarse gravel or dense moss is placed on the bottom of a shallow aquarium and a well-fed group is kept there for a few days. It spawns in the early morning hours. After the adults are removed, the fry become free-swimming within a few days; they are fed infusoria and then newly hatched brine shrimp.

Very hardy. Jumping out of a cramped tank without a lid is the most common cause of loss. Poor water quality can lead to white spot and fin rot; do 25–30% water changes weekly.

Males are slimmer; the orange-red line on the body and the warm tones in the fins are brighter. Females have a fuller belly and are slightly paler.