This file contains data on numerical abundance of mesopelagic fishes collected in April 2015 across the tropical and equatorial Atlantic. Twelve stations were visited day and night, from the oligotrophic region close to the Brazilian coast to the more productive region off the western African coast. Hauls were performed with a scientific midwater trawl, the Mesopelagos (designed by Meillat, 2012), which works with a single traction cable. The gear consists of graded-mesh netting starting with 30 mm and ending with 4 mm. At the end of the net, a multi-sampler (designed for the present investigation by one of the co-authors, A. Castellón-CSIC) was installed to obtain samples from 5 different depth layers of the water column. For some stations, where lots of gelatinous organisms, or Sargassum weed occurred, the system could not work and the data presented integrates the water column from 800 m to the surface. The depth of the net was controlled by a SCANMAR system. Samples were identified on board or frozen for a later identification in the laboratory. These data were obtained within the project: "Migrants and Active Flux In the Atlantic Ocean, financed by the Spanish Ministerio de Ciencia e Innovación CTM2012-39587-C04
