OCEANARIUM Predictable annual aggregation of longnose parrotfish (Hipposcarus harid) in the Red Sea J. Spaet Received: 2 March 2013 / Revised: 23 April 2013 / Accepted: 14 May 2013 # Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2013 Longnose parrotfish (Hipposcarus harid) routinely ag- gregate in large schools once a year during the spring (Gladstone 1996) in a shallow lagoon in the Farasan Islands (16°43′44.16″N, 42°4′24.47″E) of the Southern Red Sea. Known to locals for the past two centuries, this aggregation is the reason for Saudi Arabia’ s tradi- tional Hareed Festival ( ه ﺠ ا ن ا ﺤ ي ﺪ). Between April 7 and 13 2012, 7–12 schools arrived in the lagoon. Schools were 3–4 m in diameter (Fig. 1a) and contained approximately 200–500 tightly-packed individuals (20– 30 cm total length) (Fig. 1b). All fish displayed pale, initial phase coloration except for one terminal-phase individual per school. No schools of parrotfish were observed in open waters outside the lagoon area. In preparation for the Hareed Festival, on the 5th day of the aggregation, when most schools have arrived, local fishermen trap 3,000–5,000 parrotfish in the lagoon. Following tradition, hundreds of local people then gath- er along the shore. Equipped with nets, they await a starting signal and then rush into the lagoon (Fig. 1c). Whoever catches the largest biomass is awarded prize money from the prince of the Farasan region, again following a long tradition. Caught fish, which seem to be in unripe condition (no running eggs or milt ob- served) are then given away as presents to relatives and friends, consumed by the winners, or get discarded as the selling of the catch is by festival rules not permitted. After approximately 60 min, there are no live fish remaining in the enclosed area. Despite this intense harvesting, the aggregation still arrives every year. The Farasan Islands are the only known location in the entire Red Sea where parrotfish aggregate in the Fig. 1 a School of parrotfish in the area netted-off for the Hareed Festival, b surface view of individuals in one of the schools, c local people harvesting parrotfish J. Spaet (*) Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia e-mail: julia.spaet@kaust.edu.sa Mar Biodiv DOI 10.1007/s12526-013-0162-7