mouth-brooder, Senegal - pega, Indian remora
- mouth-brooder, Senegal
- mouth-brooders, African
- mower
- mudcreeper
- mudcreepers
- mudfish
- mudfish, black
- mudfish, brown
- mudfish, Canterburu
- mudfishes
- mudhopper, blue
- mudhoppers
- mudminnow, central
- mudminnow, eastern
- mudminnow, European
- mudminnow, Olympic
- mudminnow, western
- mudminnows
- mudskipper
- mudskippers
- mudsucker, golden
- mudsucker, longjaw
- mudsucker, purple
- mudsucker, red-nosed
- mudsucker, sailfin
- mudsuckers
- mudtrout, Tasmanian eel
- muksun
- mulhaden
- mullet, bastard
- mullet, black
- mullet, Black Sea
- mullet, black-finned
- mullet, blue-tailed
- mullet, blueback
- mullet, bluespot
- mullet, bluespot gray
- mullet, blunt-snouted
- mullet, borned
- mullet, Buchanan’s blue-tailed
