Highlighting the species diversity, pricing trends, and conservation concerns in a major ornamental fish hub

The global ornamental fish trade presents significant challenges to conservation of biodiversity. Here we explore patterns in the freshwater ornamental fish market in Hong Kong, a major wildlife trading hub. Weekly surveys over three-months in the primary aquarium district documented 540 freshwater fish species from 73 families. We found that species occurrence in the market was largely price-driven, and minimum retail price was the strongest predictor of their frequency of occurrence. Along the occurrence-price gradient, we found that potentially undescribed species dominated the rare/expensive end of the market, potentially influenced by the anthropogenic allée effect. Alarmingly, 86 species (16%) were potentially undescribed, while 38% were either not evaluated or classified as Data Deficient by the IUCN. While common/cheaper species dominate the market, the substantial number of little-known species being sold is of conservation concern, underscoring the need for more extensive monitoring at the risk of losing them to unregulated exploitation.