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Search for fish species by common or scientific name, or use filters to browse by water type, size, temperament, and difficulty.
Found 555 species
Black River madtom
Noturus maydeni
Noturus maydeni is a tiny little riffle catfish from the Ozarks that lives tucked into cool, clear, fast water over gravel and rocks. Its claim to fame is being super range-limited (Black and St. Francis river drainages), and like other madtoms its pectoral spines can give you a nasty poke if you grab it wrong.
Black Skirt Tetra (Black Widow Tetra)
Gymnocorymbus ternetzi
Black skirts are those little "suit-and-tie" tetras with the dark bands and flowing fins that look way fancier than they should for how tough they are. They're super active midwater fish, and when you keep a proper group they do that tight, zippy schooling thing that makes the whole tank feel alive. Just give them enough buddies and finny tankmates they won't be tempted to nip.
Black-chest cardinalfish
Xeniamia atrithorax
A tiny deep-reef cardinalfish described in 2016 that reaches about 3.0 cm SL. It has a distinctive dark melanophore patch on the chest/isthmus region and shows male mouthbrooding (brooding eggs reported in males). Recorded from the South China Sea off central Vietnam, with later records from Taiwan; reported from ~40–119 m depth (often ~70–119 m).
Black-edge cabillus
Cabillus nigromarginatus
Cabillus nigromarginatus is a very small marine goby (to about 3 cm) described from Rodrigues in the Western Indian Ocean, with records including Seychelles; it is known as the black-edge cabillus.
Blackfin pupfish
Cyprinodon beltrani
Cyprinodon beltrani is a tiny Mexican pupfish from Lake Chichancanab, and the males get those dark fin accents that make them look way tougher than their size. These busy little substrate-pickers consume detritus and other tiny bits, and surprisingly, they can be feisty with each other, especially during male-to-male interactions.
Blackfin squeaker
Synodontis melanopterus
Synodontis melanopterus is a West African mochokid (squeaker/upside-down catfish) described as uniformly dark in coloration. Like other Synodontis, it has robust fin spines and is a bottom-associated fish that will use shelter; provide hiding places and be cautious when netting due to spine entanglement risk.
Black-Lined Loach
Ambastaia nigrolineata
Ambastaia nigrolineata is a little river-loach with two clean black stripes that turns into a really cool barred pattern as it grows. Keep it in a proper gang and you will see all the fun loach stuff - shadowing, clicking, and the occasional goofy "greying out" dominance squabble. It likes clean, well-oxygenated water and lots of nooks to cram into.
Blacktip rasbora
Rasbora dorsinotata
This is a slim little Southeast Asian rasbora with a clean dark lateral stripe and a neat black tip on the dorsal fin. In a group it gets way more confident and you will see that tight midwater schooling behavior, especially in a planted tank with some flow.
Blue dorsal Borneo sucker
Gastromyzon ctenocephalus
This is one of the little Borneo hillstream loaches that scoots around like a tiny living suction cup, spending most of its day grazing on biofilm off smooth rocks. The cool part is the fin patterning - the caudal fin has bold pale-blue striping, and they do those quick little territorial "flaring" displays with each other without usually doing real damage. Keep it in a high-oxygen, high-flow setup and it just settles in and does its thing.
Blue Green Chromis (Green Chromis)
Chromis viridis
Blue Green Chromis are those shimmery little green-blue darts you'll see zipping around the top of a reef tank, always looking like they're catching the light just right. They're super fun in a group because they hover and cruise together, but they've got a bit of a "pecking order" thing going on if the tank's tight or the group's too small.
Blue gularis
Fundulopanchax sjostedti
This is the big, flashy West African killifish with the ridiculous triple-point tail and electric blue-green body covered in red spotting. Males can be real attitude machines with each other, but if you give them room, cover, and a tight lid, they make an awesome centerpiece fish that will absolutely demolish live and frozen foods.
Blueband goby
Valenciennea strigata
This is that classic gold/yellow-headed sand-sifting goby with the little blue cheek stripe-always busy, always rearranging your sandbed. In a reef tank it'll spend the day taking mouthfuls of sand, filtering out tiny critters/foods, then "snowing" clean sand back out, and it'll usually claim a burrow area (often as a pair in the wild). It's super cool behavior-wise, but you really do need a mature tank with a proper sandbed and a lid because they can jump.