| Mackerel sharks |
| Mackerels |
| macro- |
| macro-algae |
| macrobenthos |
| macroclimate |
| macrofauna |
| macrophagous |
| macrophthalmia |
| macrophyte |
| macrophytes |
| macroplankton |
| macrosmatic |
| Madeira |
| Madura anchovy |
| Mahseer |
| maiden |
| mainframe |
| mainstream flow |
| maintenance food consumption |
| Makassar fish |
| Makassar Strait |
| Malacca Strait |
| malar |
| malar thorns |
| malassol |
| Mam-ruot |
| Mammalia |
| mammose |
| mandible |
| mandible length |
| mandibular symphysis |
| Manefishes |
| mangrove |
| Mannitol |
| Manta rays and devil rays |
| many deep passes/open atoll |
| map |
| marbled |
| Marbled catfishes |
| Marblefishes |
| margin |
| marginal habitat |
| marginaria |
| mariculture |
| Marinade |
| marinate |
| marine |
| marine notch |
| Marine Protected Area |
| marine realm |
| Marine Research Section |
| Marine Science Institute of Andalusia (ICMAN) |
| marine snow |
| Marinerad stekt sill |
| Marinoitu silakkarulla |
| mark-recapture study |
| marked |
| marketable size |
| marsh |
| marsupium |
| masculinisation |
| mass selection |
| mating |
| mating event |
| mating scars |
| mating system |
| Matje cured herring |
| matje herring |
| matriachal family |
| matriarch/patriarch family |
| matrix |
| matroclinous inheritance |
| matrotrophic viviparity |
| Matthiessen's ratio |
| Mattie |
| maturation |
| maturity |
| matutinal |
| Mauthner's axon |
| maw bladder |
| maxilla |
| maxillary |
| maxillary extension |
| maxillary length |
| maximum age |
| maximum economic yield |
| maximum equilibrium catch |
| maximum length |
| maximum potential yield |
| maximum standing crop |
| maximum sustainable yield |
| maximum weight |
| maximum yield-per-recruit |
| Meander |
| mechano-receptor |
| Meckel's cartilage |
| medial |
| medial cartilage |
| medial view |
| median |
| Median effective concentration |
| median fin |
| median fins |
| median length |
| Median lethal concentration |
| median predorsal scales |
| median valley |
| medicated feed |
| mediolateral |
| Mediterranean cure |
| Mediterranean Sea |
| medithermal |
| medulla oblongata |
| medusa |
| Medusafishes |
| megadiversity countries |
| megalopa |
| Megamouth sharks |
| megaplankton |
| Meikotsu |
| meiobenthos |
| meiofauna |
| meiolecithal |
| meiosis |
| Meji |
| Melanesia |
| melanin |
| melaniridosome |
| melanistic |
| melanocyte |
| Melanonids |
| melanophore |
| meltwater |
| membrane |
| Memorial University, Department of Biology, Newfoundland |
| Memphis State University Museum of Zoology, Tennessee |
| Menhadens |
| menisicus |
| mental |
| mental barbel |
| menu |
| merchantable |
| mere |
| meristic |
| meristic characters |
| Merluccid hakes |
| mermaid |
| mermaid's purse |
| mero- |
| meroblastic |
| meromictic |
| meropelagic |
| meroplankton |
| Mersin |
| mesentery |
| mesethmoid |
| mesh gauge |
| mesh selection |
| mesh size |
| mesiad |
| mesial |
| meso- |
| mesocoracoid |
| mesohaline |
| mesolecithal |
| mesonephros |
| mesopelagic |
| mesophythmile |
| mesopterygium |
| mesorchium |
| mesosaline |
| mesothelial |
| mesotrophic |
| mesovarium |
| meta- |
| metabolic rate |
| metabolism |
| metacentric |
| metadata |
| metadatabase |
| metalimnion |
| metamere |
| metamerism |
| metamorphosis |
| metencephalon |
| metonym |
| metric ton |
| micro-climate |
| microatoll |
| microatolls |
| microbenthos |
| microencapsulated diets |
| microfauna |
| microhabitat |
| Micronesia |
| microorganisms |
| microphagous |
| micropredator |
| microprobe analysis |
| micropyle |
| microsatellite |
| microsmatic |
| microsquamose |
| microtag |
| mid-brain |
| mid-oceanic ridge |
| midbrain |
| Middle Atlantic Bight |
| midgut |
| midocean ridge |
| midwater |
| midwater pair trawl |
| midwater trawl |
| Midwestern State University |
| Miettes |
| Migaki nishin |
| migrating |
| migration |
| mild cured fish |
| mild smoked fish |
| Milker herring |
| Milkfish |
| milleporine |
| milt |
| milt sauce |
| milter |
| Milwaukee Public Museum, Wisconsin |
| mimetic |
| mimic |
| minced fish |
| minimum biological acceptable level |
| minimum landing size |
| minimum mesh size |
| minimum size |
| Minimum Viable Population |
| minnow |
| Minnows or carps |
| minor commercial |
| Miocene |
| Mirin |
| misidentification |
| misreporting |
| Mississippi Museum of Natural History, Mississippi |
| Mississippi State University, Mississippi |
| Missouri Department of Conservation, Missouri |
| mitochondria |
| mitochondrial DNA |
| mitosis |
| mixed fishery |
| mixohaline |
| mixolimnion |
| mixoplankton |
| mixosaline |
| moat |
| moat and depression |
| modal |
| modal size |
| mode |
| model population |
| modem |
| moist pellet |
| Mojama |
| Mojarras |
| molar |
| molariform |
| Molas |
| Mollusca |
| molluscs |
| Moluha |
| Molukka Sea |
| monandric |
| monandry |
| Monikendammer |
| monk |
| mono- |
| Monocotyledoneae |
| monoculture |
| monocyclic fish |
| monoecious |
| monogamy |
| monognathic |
| monomictic |
| monomorphic |
| monophagous |
| monophyletic |
| monosex |
| monospecific |
| monospondylous |
| monospondylous precaudal vertebrae |
| monospondylous-diplospondylous transition |
| monotelic |
| monothetic key |
| monotypic |
| monotypy |
| montane |
| moochim |
| mooching |
| Mooneyes |
| Moonfish |
| Moonfishes or fingerfishes |
| Moorish idol |
| Moray eels |
| Morid cods |
| morph |
| morphology |
| morphometric |
| morphometric character |
| morphometric characters |
| mortality |
| morula |
| Morwongs |
| Moss Landing Marine Laboratories, California |
| mother ship |
| Mother-of-pearl |
| mottled |
| mountain processes |
| mouth |
| mouth brooder |
| mouth brooding |
| mouth width |
| Mozambique Channel |
| MS-222 |
| muciferous |
| mucin |
| mucophagy |
| mucosal fold |
| mucous canal |
| mucous gland |
| mucous membrane |
| mucronate |
| mucus |
| mud |
| Mud fish |
| mud taste |
| muddy flavour |
| Mudminnows |
| Müllerian mimicry |
| Mullets |
| multicuspid |
| multicuspidate |
| multimedia system |
| multiserial |
| multitasking |
| multivoltate |
| muria |
| Murphy's Law |
| Murray State University, Kentucky |
| Musci |
| Musée d'Histoire naturelle, La Chaux-de-Fonds, Switzerland. |
| Musée d'Histoire naturelle, Neuchatel, Switzerland |
| Musée Guimet d'Histoire naturelle de Lyon |
| Musée Océanographique, Monaco |
| Musée royal de l'Afrique centrale, Tervuren |
| Musée zoologique de l'Université Pasteur et de la Ville de Strasbourg |
| Museo civico di Storia naturale "Giacomo Doria", Genova, Italy |
| Museo civico di Storia naturale, Carmagnola, Italy |
| Museo civico di Storia naturale, Milano |
| Museo civico Storia naturale, Verona, Italy |
| Museo de Ciencias Naturales |
| Museo di Storia naturale dell'Università, Firenze, Italy |
| Museo Nacional de Ciencias Naturales, Madrid |
| Museu Bocage, Lisboa |
| Museu de Biologia, Universidad Central de Venezuela |
| Museu de Zoologia, Universidade de Sao Paulo, Brazil |
| Museu municipal do Funchal (Natural History), Madeira, Portugal |
| Museul de Istorie Naturala "Grigore Antipa" |
| Muséum d'Histoire naturelle, Bordeaux |
| Muséum d'Histoire naturelle, Geneve |
| Muséum d'Histoire naturelle, La Rochelle |
| Muséum d'Histoire Naturelle, Saint-Denis, Ile de La Réunion, France |
| Museum für Naturkunde der Humboldt-Universität, Zoologisches Museum, Berlin |
| Muséum national d'Histoire naturelle, Paris |
| Museum of Natural History, Wroclaw University, Wroclaw, Poland |
| Museum of Southwestern Biology, University of New Mexico, Albuquerque |
| Museum of the Institute of Marine Biology, National Sun Yat-Sen University |
| Museum of Zoology, Lund, Sweden |
| Museum of Zoology, University of Bergen |
| Mustard herring |
| mutagen |
| mutualism |
| myelenocephalon |
| myelin |
| myomere |
| myomere count |
| myomere formula |
| myomeres |
| myoseptum |
| myotome |
| Myriapoda |
| mysids |
| myxopterygium |
