Large shoals of anchovies are uncommon around Indonesia, and so Thomas knew he was witnessing something special when he saw an enormous shoal encircling a rock off Indonesia's West Papua province. As he approached, it separated like a curtain and encircled him in a fountain formation. This revealed a group of longfin batfish close to the rock, and below them fusiliers and jacks. Fish shoal to form one alert whole, and predators and potentially dangerous animals would normally be on the outside, but here the larger fish - and Thomas - were surrounded. 'It was a tricky scene to encompass in one image,' says Thomas, but he did manage to catch both the moment and the behaviour.
Nikon D300 + Tokina 10-17mm f3.5-4.5 lens at 10mm; 1/60 sec at f8; Subal housing + domeport; 2x Subtronic Nova strobes.
West Papau, Indonesia