Pearl danio

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Eats anything. Flake, micro pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia, live food. Surface and midwater feeder. Not picky, not slow. Feed twice daily. The iridescent pearl coloring shows best on a varied diet.

Compatibility

• Active, peaceful schooling fish. One of the prettier danios but overshadowed by the more widely available zebra danio. Groups of 6+ for proper schooling.
• Compatible with most peaceful community fish: tetras, rasboras, barbs, corydoras, and gouramis. Active swimmers that need horizontal space.
• Tolerates cooler water (18–25°C), making them suitable for subtropical setups alongside white clouds, rosy barbs, and paradise fish.
• Jumpers. Like all danios, they leap when startled or during play. A lid is necessary.

Origin and habitat

The pearl danio, Danio albolineatus, is a slim, active schooling fish widespread across mainland Southeast Asia and Sumatra, recorded from Myanmar and Thailand through Laos, Cambodia, Vietnam, and Peninsular Malaysia, in major drainages like the Irrawaddy, Salween, Mekong, Mae Klong, and Chao Phraya as well as many smaller streams. It lives near the surface of clear hill streams and small rivers. The species name albolineatus means white-lined, for the pale stripe along the flank, but the draw is the iridescent body that shifts between pink, blue, and gold with the light. Recent work has moved a number of the small danios into the genus Brachydanio, so the fish is increasingly listed as Brachydanio albolineata. Aquarium fish usually reach about 6 to 7 cm, though records show a larger maximum. It is a subtropical species that prefers the cooler end of the tropical range, which makes it a good fit for unheated or lightly heated community tanks. Golden, near-albino forms are common in the trade, and the blue-red striped and Kedah forms, once treated as varieties, may turn out to be separate species.

Breeding

An easy egg scatterer along standard danio lines. A conditioned group spawns at dawn over fine-leaved plants or a spawning mop, dropping a large batch of non-adhesive eggs that fall through the plants or a layer of marbles out of reach of the hungry adults, who are best removed afterward. The eggs hatch in a couple of days and the fry take baby brine shrimp within a few more, growing quickly. There are no special tricks beyond keeping the eggs away from the parents.

Common problems

There is little to go wrong. Pearl danios are hardy and adaptable, with ich on new fish the main thing to watch, treatable with standard methods. They are strong jumpers, so a cover is needed. The usual complaint is cosmetic: under harsh cool-white light over pale gravel the pearl sheen washes out, while warm light and a dark bottom bring it back. Like most small danios they live only a few years.

Outdoor pond suitability

Climate

subtropical

USDA zones

8–12 (winter low around -12°C or warmer)

Outdoor pond at least 60 cm deep for thermal mass. Local frost depth and surface freezing matter.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size