The study of the fish communities is achieved using three belt transects of 5 m x 50 m, which represents a projected surface of 250m2 each.
The transects are positioned in the same zone as the coral survey. One is directly over the photographic coral survey and the other two are positioned at 25 m on both sides of the first one at the same depth. The numbering of the transects is from 1 to 3 from right to left while looking at the coast when the transects are parallel to the coast. This is the case for all the sites except Samoa, Tiahura and Entre 2 Baies. For Tiahura and Entre 2 Baies, the transects are positioned along the spurs perpendicular to the coast and in Samoa around a pinnacle by numbering from right to left while facing the pinnacle.