This paper discusses the use of moving images in the anthropology of technique, specifically, the ethnographic recording of the capture with harpoon of arapaima fish in the coastal lakes of Amapá, in the Brazilian Amazon. Inspired in Rouch's notion of cine-trance, I ponder on the possibility of doing ethnography by intertwining the technical processes of capturing that fish and capturing images. I also describe the way in which I take the relationship between the movie camera and the harpoon - their rhythms and properties - as a helpful tool to describe the major features of the dialogical interaction between harpooner and fish, namely, the harpooner-harpoon link, the perception of signals emitted by the fish, and the meaning of the capturing gesture.