FISH OF THE WEEK - Deissner's Licorice Gourami (Parosphromenus deiss­neri)

Today we've got a blackwater fish: Deissner's Licorice Gourami (Parosphromenus deiss­neri), the Parosphromenus genus' poster child.

Deissner's Licorice Gourami was named in 1859 after F. H. Deissner, a military health officer who sent a collection of specimens to Dutch ichthyologist Pieter Bleeker. Males are gold and brown striped with sapphire blue fins, the tail fin having a noticeably long central filament that comes to a point. Females are paler in coloration and mostly brown, lacking any brightly colored fins. They are one of the largest licorice gouramis at 2 inches (5cm) in length. P. deissneri is endemic to the Bangka and Beli­tung Islands of Indonesia where it can be found in the forest's blackwater rivers and swamps at a pH ranging from 3.0-5.5. It was thought to be the only species in the genus for nearly a century, but later more licorice gouramis were found, and some such as Parosphromenus bintan (especially females) were difficult to differentiate. Due to this confusion many licorice gouramis in the international trade have been sold under the wrong names. Today, true P. deissneri are rare in the west, and any strains that do still exist in the hobby are from private imports. This species is listed as endangered by the IUCN Red List due to its restricted range and threats to its habitat such as palm oil farming and illegal deforestation. These fish along with many other blackwater species continue to decline in the wild without adequate protection from human activity.

Sources and further reading:
• https://www.parosphromenus-project.org/en/p-deissneri
• https://www.seriouslyfish.com/species/parosphromenus-deissneri/
• https://fishbase.mnhn.fr/summary/12078
• https://www.parosphromenus-project.org/en/rediscovery-of-the-sapphire-from-bangka-parosphromenus-deissneri