Vendors started selling pet fish near the Mong Kok MTR station in the 1950s; keeping them became hugely popular in the mid-1970s when the economy took off. Some street vendors moved into shops on Tung Choi Street, the heart of today’s goldfish market.

One shopkeeper, who has been selling fish in Mong Kok for more than 60 years, blamed the steep drop in business on a lack of variety. He also said rising rents had forced some goldfish shops to close, replaced by restaurants or pet stores.

Van den Eijnden says he took several days documenting the market itself – the vendors, and stores opening and closing. He also wanted to focus on “little portraits of these anonymous fish”, so he captured them against a white background.

It was the first time Van den Eijnden had branched out from his usual human portraits; his most recent project, lasting three years, focused on kickboxers.

He says he initially struggled with vendors who didn’t understand what he was doing. Many of the stores have signs asking visitors not to take pictures. But after van den Eijnden showed them the fish photos on his phone, they left him alone.

The photographer says he is a big fan of Hong Kong, and cities in general, because “everybody is almost ignoring each other, and as a photographer this is great because you can just walk around without being noticed”.

He may return to Hong Kong to take more fish photos. He had originally planned to follow buyers home, so he could document working-class Hongkongers with a fish bowl in a small apartment, in contrast with wealthy fish owners and their grand aquariums.

Van den Eijnden says he has already curated a second photo series from his trip to the goldfish market, and hopes to display both in Hong Kong some day, to “return it to its source”.