DNA Sleuthing Reveals the Secret Diets of Hong Kong's Seabed Fish

What’s on the menu for fish dwelling on Hong Kong’s seabed? To find out, researchers have employed a sophisticated combination of DNA analysis and chemical tracing to peer into the stomachs of 16 demersal, or bottom-dwelling, fish species.

Using a technique called gut content metabarcoding, which identifies prey from residual DNA, the team built a detailed map of predator-prey interactions. The findings reveal a community with highly specialised tastes. Eight species, including the Japanese butterflyray, were confirmed as piscivores (fish-eaters), while six others, like the rough flathead, dine predominantly on crustaceans.

Some fish have even more unique feeding behaviours; the spotted sicklefish preys on brittle stars, while the goatee croaker prefers bivalves. This dietary diversity creates clear “trophic niche partitioning,” where species carve out their own food sources to minimise competition. This organisation is vital for the ecosystem’s stability, and this research provides a crucial baseline for future conservation efforts.