SINGAPORE - Despite its busy straits, Singapore’s position near one of the world’s most biodiverse marine areas has allowed it to yield a surprising variety of fishes, though their significance is occasionally lost on those who catch them.

Such was the case at Bedok Jetty in August, when an angler mistook a globally endangered zonetail butterfly ray (Gymnura zonura) for the average stingray. The butterfly ray is distinguished by its wide, triangular body and short tail, compared with the rounder body and long tail of more common stingrays.

Fellow fishing enthusiast Brian Sng, a Singapore Management University software engineering student, quickly realised the value of the catch from the photo he was shown, and informed the angler of his rare find.

To avoid these cases of mistaken identities, Sng, 21, and a group of fellow enthusiasts interested in the scientific study of fish built a free mobile app to help people identify the fishes that live in Singapore’s murky waters.

On Sept 17, the Ichthyological Society of Singapore (ISS), which has more than 150 members, launched SGFish on the Apple App Store. The app can identify more than 900 species using an image recognition model.

Users snap a photograph of their catch via the app, and the program will identify the species. It will also log down where each find was made.

To maintain scientific integrity, volunteers and co-fou...