Alosa to detect ultrasound (at frequencies above 20 kHz, which is the limit of human hearing). This was first discovered by fisheries biologists studying a type of shad known as blueback herring, and was later verified in laboratory studies of hearing in American shad. This ability is thought to help them avoid dolphins that find prey using echolocation. "Alosa" species are generally pelagic. They are mostly anadromous or semianadromous with the exception of strictly freshwater landlocked species. "Alosa" species are generally migratory and schooling fish. Males usually mature about a year before females; they spawn in the late spring to summer.
Guinean sea catfish Guinean sea catfish The Guinean sea catfish (Carlarius parkii), also known as the Marine catfish, is a species of sea catfish in the family Ariidae. It was described by Albert Günther in 1864, originally under the genus "Arius". It is a tropical fish which is found in Mauritania, Angola, Morocco and the Spanish Sahara. It inhabits coastal marine waters at a depth range of , also frequently entering estuaries and freshwater rivers. It reaches a maximum total length of , more commonly reaching a TL of . The Guinean sea catfish feeds on bony fish and shrimp. It is of