Search Species
Search for fish species by common or scientific name, or use filters to browse by water type, size, temperament, and difficulty.
Found 665 species
Spindle Yunnan loach
Yunnanilus elakatis
Yunnanilus elakatis is a nemacheilid (stone loach) endemic to Yunnan, China (type locality: Yiliang County). Aquarium-specific husbandry data for this exact species is scarce in major references; when kept, it should be maintained like other small stream-associated stone loaches: high water quality, good oxygenation, and a fine, smooth substrate with cover.
spinycheek sleeper
Eleotris valadei
A neat little sleeper goby from Madagascar and nearby islands, this guy hangs out on the bottom like a bulldog and waits to pounce on bite‑sized prey. It is amphidromous in nature, so adults live in fresh water but the species uses estuaries in its life cycle, and it will absolutely snack on tiny fish or shrimp.
Spiny grenadier
Coelorinchus parallelus
A deep-sea rattail with a long whip tail and spiky head ridges, it cruises 600-1000 m down around Japan, the East China Sea, and the Philippines. It even has a tiny light organ near the belly, which is wild to see in photos. Super cool fish to read about, but not one to keep at home since it wants near-freezing saltwater and deep-ocean conditions.
Spotfin betta
Betta macrostoma
This is the famous "Brunei beauty" wild betta - a chunky, orange-red fish with an awesome little eyespot on the dorsal fin and a big attitude-free personality (until you put two males together). The really cool part is breeding: the male is a paternal mouthbrooder, and the pair does that weird "kiss" egg transfer behavior people geek out over.
Spotfin cardinal
Jaydia queketti
This is a small marine cardinalfish from the western Indian Ocean with a really recognizable black eyespot on the first dorsal fin and a pattern of brownish spots that line up into messy stripes. It is a nocturnal zooplankton feeder that hides in rocky areas by day, then comes out after lights-out, and males mouthbrood the eggs.
Spothead lantern fish
Diaphus metopoclampus
This is a deep-sea lanternfish with rows of photophores (little light organs) that it uses down in the dark, and it does that classic up-at-night, down-by-day vertical migration. Super cool animal, but its whole lifestyle is built around cold, high-pressure midwater life, so its not really an aquarium fish in any normal sense.
Spotted blue-eye
Pseudomugil gertrudae
This little blue-eye is one of those fish that looks "cute" at first glance, then you notice the electric-blue eyes and the males flashing those spotted fins at each other all day. They're happiest in a planted, kind of shady tank with gentle flow, where they'll cruise in a loose group and do constant mini courtship displays.
Spotted Mandarin Dragonet (Picturesque/Psychedelic Mandarin)
Synchiropus picturatus
This little dragonet is basically a living piece of reef art-chunky fins, goofy "hovering" swimming, and those crazy psychedelic spots that look painted on. The big thing with them is they're constant pickers, cruising rockwork all day hunting tiny critters, so they're happiest in a mature tank with tons of pods (or a keeper who's ready to meet them halfway on food). If you like chill fish with tons of personality that don't bother anyone, mandarin time is hard to beat.
Spotted robust triplefin
Forsterygion capito
This is a little New Zealand triplefin that hangs out in rock pools and shallow sheltered reefs, perched on rocks and scooting around to hunt tiny critters. The cool part is the breeding behavior - the male sets up and guards a nest under a rock, and they can darken up a lot in season.
Spotted spikefish
Hollardia meadi
Hollardia meadi is a tiny deepwater spikefish from the western Atlantic with a super cool pink-and-spot pattern and those lockable spines that make the whole family look like little armored oddballs. Its a rocky-bottom, reef-associated fish that lives way deeper than typical reef tank temps, so its basically a no-go for normal home aquariums unless youre set up for chilled deepwater marine.
Spotted tinselfish
Xenolepidichthys dalgleishi
This is a quirky deepwater tinselfish with a shiny silver body sprinkled in black polka-dots. Juveniles sport crazy-long fin spines, and the species lives way down the continental slopes in cold, dim water. It is a marine oddball and not a realistic home-aquarium fish.
Spotted Vanmanenia (hillstream loach)
Vanmanenia maculata
This is one of those true hillstream loaches that lives in fast, clean river flow, and it is built like a little suction-cup torpedo for clinging to rocks. The patterning is the fun part - you get those pale-centered dark spots/bars that break up the body and help it vanish on stone. It does best in a "river tank" with lots of oxygen and current, where it spends the day grazing biofilm and generally minding its own business.