Fish Out Of Water

Patrolling its stretch of mudflats, the territorial mudskipper defends a habitat that’s neither land nor sea.

- Helen Scales

Life is tough in a halfway world between land and sea, especially for the little fish that inhabit tropical mudflats. Mudskippers have to endure extreme heat and the sticky, salty mud, plus daily flooding and exposure as the tides rise and fall. Not only must they find ways to survive as fish out of water but, to make matters worse, this is a crowded place, filled with rivals to fight and predators to avoid. It’s every walking, jumping fish for itself.

“The big expanses of mud seem monotonous at first,’’ says wildlife photographer Rémi Masson, who has spent hours lying on scorching mudflats on Kyushu Island, in southern Japan, immersing himself in this inhospitable realm. “My biggest surprise was discovering the incredible diversity of species living there. It’s a fascinating spectacle.”

As the water retreats each day, egrets and other wading birds fly in and stalk across the mud searching for prey. Fiddler crabs skitter around and a territorial species of mudskipper, known in Japan as matsugoro, emerge from their borrows in the mud. The fish are a handspan in length and defend a territory 2m across, roughly the area of a pool table. When a crab wanders too close, it receives a stern warning from the resident mudskipper, which raises two blue, spotty fins along its back and opens its big, gaping mouth – a sign that the crab should back off.

Things get more heated when the intruder is another mudskipper. At first, the quarrelling pair put on an intimidating display, dorsal fins raised and mouths open wide. If neither retreat, then a short, sharp skirmish breaks out and the fish leap at each other, wrestling and biting. “The fight scenes are really difficult to photograph,” says Rémi. “They happen very quickly.”