Fish Species Starting with M
Browse all aquarium fish species with scientific names beginning with "M". Each profile includes care requirements, water parameters, tank size recommendations, and compatibility information for freshwater, marine, and brackish species.
The letter 'M' features a diverse array of aquarium species, ranging from popular community favorites to unique exotic fish. Notable entries include the vibrant Boeseman's rainbowfish (Melanotaenia boesemani) and the charming Ram cichlid (Mikrogeophagus ramirezi). Whether you are interested in schooling fish like the Serpae Tetra (Megalamphodus eques) or the intriguing Fire eel (Mastacembelus erythrotaenia), this section showcases species that can enhance both beginner and advanced aquariums.
9 species found
Fire eel
Mastacembelus erythrotaenia
Fire eels are those big, snake-y "spiny eels" with the red/orange flame striping that really pops once they settle in and color up. They love to wedge themselves under wood or burrow into sand and then come out at dusk to cruise around and beg for food-super personable once they trust you, but they get huge and can absolutely inhale small tankmates.
Serpae Tetra
Megalamphodus eques
Serpaes are those fiery little red tetras with the black "comma" behind the gill-super eye-catching in a planted tank. They're active and a bit spicy, so they do best in a real group where they'll squabble with each other instead of nipping slower tankmates. When they're settled in, you get this constant cruising-and-chasing vibe that makes the tank feel really alive.
Boeseman's rainbowfish
Melanotaenia boesemani
Boesemani rainbows are basically little swimming fireworks once they settle in-males get that wild split-color look (blue up front, orange in back) and they'll flash and posture at each other all day. They're super active and way happier in a real group with a long tank to cruise, not a cramped setup where they can't stretch out.
Dwarf Neon Rainbowfish
Melanotaenia praecox
These little rainbows are like living sparks-electric blue bodies with those punchy red/orange fins, and they look even better the more you keep together. They're constantly cruising the mid-water, flashing at each other and doing that classic rainbowfish "look at me" shimmy, especially when the lights first come on or at feeding time.
Neon Green Rasbora
Microdevario kubotai
This is that tiny, glassy-yellow fish that turns into a little green highlighter once it settles into an aquarium-especially over a dark substrate and under decent lighting. They're super active mid-water shoalers, and the whole group "flashing" that neon stripe together is the main event. Keep them in a proper group and they get way bolder and look a lot more intense.
Ram cichlid (German blue ram / butterfly cichlid)
Mikrogeophagus ramirezi
Rams are tiny little cichlids with big-time attitude (in the cutest way) and insane sparkle-those blues, yellows, and that black face bar really pop when they're happy. They're also one of the warmer-water dwarf cichlids, and they'll show off pair behavior and even spawn on flat stones if you keep the tank clean and calm.
Diamond Tetra
Moenkhausia pittieri
Diamond tetras are one of those fish that look kind of plain in the bag, then you get them settled in and they start throwing off this glittery, diamond-like shine when the light hits them-super satisfying to watch. They're active, always cruising around the midwater, and in a nice little school they'll do that tight, synchronized swimming thing that makes the tank feel alive.
Silver moony (Mono)
Monodactylus argenteus
Silver moonies are those shiny, diamond-shaped "mono" fish you see cruising nonstop in brackish tanks-super active and way more fun to watch when they're in a proper group. They start out in estuaries (often sold too small and too fresh), and the big "gotcha" is they really want you to ramp them up to stronger brackish/near-marine as they grow. Feed them like a hungry, messy omnivore and give them swimming room, and they're absolute show-stealers.
African moony
Monodactylus sebae
This is that shiny, diamond-shaped "mono" that cruises around in a tight pack and looks like a little silver dinner plate with black bars when it's young. The big thing with African moonies is they're euryhaline-so they'll tolerate freshwater as juveniles, but they really shine long-term in brackish (and can be transitioned toward marine as they mature). Give them a big, open tank and a group, and they turn into nonstop, super fun midwater swimmers.