Pronunciation: /ˌmɛsə(ʊ)pɪˈladʒɪk, ˌmɛz-, ˌmiːs-, ˌmiːz-/
adjective
Biology-
(of fish and other organisms) inhabiting the intermediate depths of the sea, between about 200 and 1,000 metres (approximately 650 and 3,300 ft) down: many mesopelagic fish species have swim bladders