A new app will help people better understand Hong Kong’s rich biodiversity and appreciate its freshwater species, many of which are threatened. The Pocket Guide to Freshwater Species of Hong Kong, in English and Chinese, identifies up to 138 species of birds, fish, snakes, insects and spiders. It was developed by the Freshwater Collective, a non-profit project that encourages conservation, education and research into freshwater ecology. “The idea for the app was hatched during a dinner conversation with my high-school friend, Matthew Ng, a veterinary surgeon who learned how to code the entire app from YouTube,” says Freshwater Collective founder Jeffery Chan. “I liaised with researchers, universities and various organisations to form a coalition of local freshwater-animal experts so we had the most scientifically accurate layperson information […] There was no up-to-date resource for many freshwater animals in Hong Kong,” he says, adding that the most recent comprehensive guide on freshwater fish was produced by the Agriculture, Fisheries and Conservation Department (AFCD) in 2004. Chan says much of the damage to freshwater life in Hong Kong occurred in the late 1990s and early 2000s, with the large-scale construction of concrete channels and damming of streams and rivers. “Channelisation turned natural watercourses into lifeless concrete slabs, with little to no water, making it difficult to sustain life,” he says, adding that many species, such as the common water monitor ( Varanus salvator ), rough-skinned floating frog ( Occidozyga lima ) and white cloud mountain minnow ( Tanichthys albonubes ) have become extinct in Hong Kong owing to habitat loss. While environmental laws have slowed damaging development, Chan says threats now come from poaching for the pet trade and species taken for medicinal purposes and hobbyist aquariums. “Sadly, many people catch wild animals for pets,” he says. “Many populations of unprotected, rare or beautiful fish, such as gobies in the same family [ Sicydiinae ] as the neon goby listed in our app, have been completely wiped out, as people catch them for aquariums. “The native turtle population in Hong Kong is only 5 per cent to 10 per cent of what it used to be because people have hunted them to near extinction for medicinal purposes or for the pet trade. Dozens of turtle traps can even be found in streams within protected country parks.” He asks that anyone who spots illegal wildlife traps, poachers or pollution report it to the AFCD by calling 1823. Education is the key to protecting local species from extinction and to long-term conservation management, Chan says. “Someone who appreciates how pretty an endangered flowering plant is does not understand the implication of picking it and taking it home, which happens more often than you might think. Once people understand the implications of their actions, they will know how to react to wildlife.” He says the app will be used by local organisations such as Outdoor Wildlife Learning Hong Kong for environmental education. Individuals can help protect wildlife by not feeding animals or catching or taking home protected species and by not littering and picking up rubbish left by others. He also recommends choosing eco-friendly sunscreen and other products. “Many times I’ve arrived at streams to find a layer of sunscreen oil on the water surface. This is toxic to many animals and will directly harm them,” he says. The Pocket Guide to Freshwater Species of Hong Kong app is available for free download on Android and iOS.