Devario (Danio) pathirana

Possibly the most stunning of all danionins, Devario pathirana is rarely seen, but well worth looking out for in the shops, says Matt Clarke.

Scientific name: Devario (Danio) pathirana
Origin: This very rare species is found in Sri Lanka's Nilwala River and its tributaries.
Size: Smaller than many other Devario species at around 5-6cm".
Diet: Insectivorous, but wild fish also eat detritus, zooplankton and fry.
Habitat: According to Pethyigoda, D. pathirana lives in groups of three to five in the surface waters of fast-flowing streams. It's usually found over pebbles or boulders and rarely enters still waters or areas with a sandy or silty bottom.
Water: The pH of the waters of the Nilwala vary from 6.5-7.5, and the fish appear happy in soft, acidic or slightly neutral water.

Aquarium: These peaceful fish suit a community tank or South-east Asian biotope with a powerful filter and turbulent flow. Due to their conservation status (see Notes), it's worth having a crack at spawning them.
Devario usually scatter around 200 eggs on vegetation in shallow water. Eggs hatch in 24-48 hours, depending on temperature, and are free-swimming a few days later. Adding cold water encourages spawning. The parents need to be removed as they will try to eat the eggs and fry during and after the spawning. My group has recently spawned. The females are noticeably fatter than the males prior to spawning but the colours of both sexes are similarly striking.
Notes: This stunning danionin (member of the subfamily Danioninae) was described by Kottelat and Pethyigoda in 1990 and was previously considered to be a member of the Danio genus. They are critically endangered in the wild and are listed on the latest IUCN Redlist for fishes. According to Pethyigoda, the trade has restricted exports to very low levels to protect the population, and aims to breed the fish commercially. The species is now being bred for the aquarium trade by Orna Fish of Sri Lanka.
Similar species: Taxonomically, they are closely related to D. regina and D. malabaricus.
Availability: I've wanted some for years after seeing them in PFK, which John Rundle had obtained in the 1990s. These at Dundee's House of Pisces were the first I'd seen for sale. I recently obtained my group as a special order from Maidenhead Aquatics at Harlestone Heath.
Price: Prices range from 5-15 each.

This article was first published in the September 2004 issue of Practical Fishkeeping magazine.