Additional file 2: Video S1.

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Food competition between Atlantic mollies (P. mexicana) and sulphur mollies (P. sulphuraria). The site is a mixing zone between sulfidic and non-sulfidic microhabitats with apparently low sulfide content. Silvery fish with a white abdomen and dark bars on the flanks and caudal peduncle are P. sulphuraria while beige individuals are P. mexicana. Also note the presence of some Astyanax aeneus searching for food between the mollies. Fish were recorded on the 24^th of April 2016 with a Canon XF200 at full HD resolution with 50 fps and a polarizing filter attached. (MP4 13.6 mb)