Search Species
Search for fish species by common or scientific name, or use filters to browse by water type, size, temperament, and difficulty.
Found 562 species
River garfish
Zenarchopterus xiphophorus
This is a slim, surface-hugging halfbeak from the mouth of a river in Sumatra, and it has that classic "half-beak" look where the lower jaw sticks out. Its biology is way more "wild fish" than "pet shop fish" - think open-water cruising up top and spooking easily if the tank is busy or uncovered.
River garfish (halfbeak)
Zenarchopterus clarus
Zenarchopterus clarus is a true halfbeak - that long lower jaw is built for picking stuff off the surface. Its a tropical, surface-cruising fish from the Western Central Pacific (Thailand and Borneo), and it reproduces via internal fertilization with ovoviviparous young.
Rosen's Hybrid Platy
Xiphophorus roseni
Xiphophorus roseni is a Mexican livebearer that shows up in the hobby mostly as a "weird/obscure Xiphophorus" rather than a mainstream platy or swordtail. The big twist is that a lot of sources treat it as a natural hybrid form (often discussed as variatus x couchianus), so it is more of a "locality oddball" than a clearly distinct, widely traded species.
Rosy Tetra
Hyphessobrycon bentosi
Rosy tetras are those little coppery-pink characins that look kinda "glowy" when the light hits them right, and the males can get nice extended fins when they're settled in. Keep a small group and you'll see them do their little pecking-order sparring and flashing-nothing scary, just classic tetra drama that looks awesome in a planted tank.
Roule's abyssal cusk
Barathronus roulei
Barathronus roulei is a deep-sea bythitid/brotula-type fish from the Northeast Atlantic, recorded from deep water (e.g., ~1349 m). It is extremely rarely encountered and not an aquarium species due to collection and decompression/pressure constraints.
Roule's smooth-head
Rouleina livida
Rouleina livida is a deep-sea slickhead (family Alepocephalidae) that lives way down in the bathypelagic zone, not something you will ever see in the aquarium trade. It tops out around 34 cm standard length and has those classic deep-sea vibes like huge eyes plus little light organs (photophores) around the head and jaw.
Royal gramma
Gramma loreto
Royal grammas are that classic purple-to-yellow Caribbean basslet that likes to claim a cave and hover around it (sometimes totally upside-down under a ledge). They're usually chill with tankmates, but they can get spicy with other grammas/basslets/dottybacks if space is tight-give them rockwork and a "home" cave and they settle right in.
Ruaha kneria
Kneria ruaha
Kneria ruaha is a small Tanzanian freshwater shellear (Kneriidae) from the Ruaha River basin. It inhabits cool, quiet stream sections and feeds on detritus in the wild; aquarium husbandry guidance is sparsely documented, so keep in a mature, oxygen-rich tank and offer a varied small sinking diet alongside natural grazing.
Rubenstein's nannocharax
Nannocharax rubensteini
This is a tiny Congo Basin distichodontid that stays really small and has that sleek, "mini-darter" look. It tends to hang in the water column and pick at small foods, and it really shines in a calm, well-oxygenated setup with plenty of cover and a small group of its own kind.
Ruitoque pencil catfish
Trichomycterus ruitoquensis
This is a tiny Colombian Trichomycterus (a pencil catfish) from cool, upland streams in the Magdalena basin. It is the kind of skinny, bottom-hugging little catfish that spends its time nosing around rocks and crevices, and its wild range is super localized around the upper Lebrija drainage.
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Rummy-nose tetra
Petitella rhodostoma (syn. Hemigrammus rhodostomus)
This is the classic rummy-nose tetra - silver body, a solid red "face," and that crisp black-and-white tail that flashes when the whole group turns at once. The red nose is a legit mood ring for water quality and stress, so when they are happy and stable, they look incredible in a tight school.
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Rummy-nose tetra
Petitella rhodostoma (Ahl, 1924) (formerly Hemigrammus rhodostomus)
This is the classic rummy-nose tetra-the one with the bright red "nose" and the crisp black-and-white tail that flashes when the whole group turns together. They're tight-schoolers, so a bigger group in a longer tank is where you really get that synchronized, hypnotic swimming. The red face also doubles as a little "health meter" since it tends to fade when they're stressed or water quality slips.