Fish That Start With O [Extensive Freshwater & Saltwater Fish Name List]

Yeah! We’ve reached fish names that start with O. This starting letter may not include as many fishes as the other letters of the alphabet, but that won’t stop us all from choosing our five faves and elaborating a little more about them and some of their important attributes.

We have ocean fish, obese fish, and even orange fish on our list, so we’re confident you’ll love learning about the fish names that begin with the letter O.

Both the scientific and common names of these fishes are included, so you may learn a lot about these amazing finned creatures. The phrases that seem like gobblygook – inside the brackets are scientific nomenclature!

5 Common Fish That Starts With O

We have chosen five amazing fish to show you how wonderful fish names that begin with the letter O could be. There is something for everyone in these common five, from cichlids to stingrays. 

Ocellated Freshwater Stingray (Potamotrygon motoro)

Ocellated Freshwater Stingray inhabits water bodies such as the Mearim basins, Orinoco, and Amazon. These rays may grow to become more than 1.5 feet long and are potentially deadly.

a close up shot of Ocellated Freshwater Stingray in an aquarium as one of the fish that starts with o

Sometimes, they’re raised in aquaria, although they’re extremely specialized, and a Potamotrygon motoro would require a very big tank. We adore the Ocellated Freshwater Stingray bright yellow markings, which have earned them the nickname Peacock-Eye Stingray.

Ocellated Lamprologus (Lamprologus ocellatus)

The Lamprologus ocellatus is yet another fishing starting with O in our list. This fish is a cichlid that prefers to dwell inside a shell from time to time. When protecting their territory, they might be a little violent. If you raise a shell-living Lamprologus, ensure that you have a variety of vacant snail shells on hand and that there are sufficient for every fish in the species.

Close up photo of Ocellated Lamprologus in aquarium

Since these fishes like to reside at the tank’s bottom, they should get along with species that prefer to thrive around the top or middle. To prevent aggravating a female and worrying her continuously, their male counterparts should be housed with many females.

Gourami Opaline (Trichogaster trichopterus)

The Trichogaster trichopterus has the appearance of a fabled gemstone that bestows luck and enchantment on whoever discovers it. It’s, nevertheless, a magnificent species of fish. They are a favorite fish amongst aquarium keepers, and they are excellent pets.

richogaster trichopterus

The Trichogaster trichopterus are generally calm and get along well with the other fishes, however, you ought to avoid keeping them with fishes that nibble fins since Gourami have long ventral fins that may be too tempting for certain tank companions. The Trichogaster trichopterus, like mood rings, may change hue based on their moods. Isn’t it amazing?

Oscar cichlids (Astronotus ocellatus)

Astronotus ocellatus are large males and are common aquarium fish, yet despite their intimidating look, this cichlid is not particularly vicious. However, they somewhat love to burrow into substrates, so you want to put your Oscar inside a space that isn’t very ornamented or it will be wrecked.

half shot of an Oscar cichlids in aquarium

In terms of tank companions, Astronotus ocellatus should be kept away from smaller species since they’re carnivorous and could mistake them for food. Just like one gilled swamp eel, the Oscar cichlids could be quite selfish, and when they sense their master arriving, they might also plead at the edge of the aquarium!

Otocinclus (Otocinclus affinis)

The Otocinclus affinis, commonly known as Algae Scrapers, Dwarf Suckermouth, Otto Cats, or Oto, is a kind of catfish. These small catfish enjoy scraping algae from hard substrates such as rocks and the edge of your aquarium, as you might have figured out from their last name — ideal for making your tank appear spotless.

Like the Odynea pimelodid catfish, the Otocinclus affinis are a sensitive kind of fish that can be hard to care for. They ought to be alright as soon as they are inside the acquarium and established, but they have a tendency to die suddenly after displaying no indications of illness. But there is no need to be put off by this; a fortunate Otocinclus affinis might remain your companion for more than a three hundred and sixty-five days!

List of Fish Beginning With O

Continue reading to learn about additional fish that starts with O, and you could even uncover your personal top five! If you have any of these species on this list inside your tank, then you might want to consider purchasing some from a local fish store.

Freshwater Fish Beginning With O

  • Obliquidens Hap (Haplochromis obliquidens)
  • Obese Synodontis (Synodontis obesus)
  • Ocellated Loach (Acanthocobitis urophthalmus)
  • Obscure Snakehead (Parachanna obscure)
  • Ocellated Synodontis (Synodontis ocelli fern)
  • Ocellated Shell-Dweller (Neolamprologus kungweensis)
  • Old World Knifefish (Chitala ornata)
  • Odynea Pimelodid Catfish (Pimelodella chagresi odynea)
  • One-Lined Pencilfish (Nannobrycon unifasciatus)
  • One-Gilled Swamp Eel (Ophisternon bengalense)
  • Orange Chromide (Etroplus maculatus)
  • One-Spot Synodontis (Synodontis notatus)
  • Orange-Lined Cichlid (Melanochromis joanjohnsonae)
  • Orange-Finned Loach (Botia modesta)
  • Orfe (Leuciscus idus)
  • Oregon Chub (Oregonichthys crameri)
  • Oriental Snakehead (Channa orientalis)
  • Oriental Loach (Misgurnus anguillicaudatus)
  • Ornate Ctenopoma (Ctenopoma ansorgii)
  • Ornate Bichir (Polypterus ornatipinnis)
  • Ornate Pimelodus (Pimelodus ornatus)
  • Ornate Fin Nipper (Ichthyborus ornatus)
  • Ozola Barb (Barilius barna)
  • Oxeye Herring (Megalops cyprinoldes)

Freshwater Fish Beginning With O

  • Ocean Perch (Sebastes norvegicus)
  • Oarfish (Regalecus glesne)
  • Oceanic Whitetip Shark (Carcharhinus longimanus)
  • Ocean Sunfish (Mola mola)
  • Oldwife (Enoplosus armatus)
  • Oilfish (Ruvettus pretiosus)
  • Opah (Lampris guttatus)
  • Olive Flounder (Paralichthys olivaceus)
  • Orange Roughy (Hoplostethus atlanticus)
  • Opaleye (Girella nigricans)
  • Orangestriped Triggerfish (Balistapus undulatus)
  • Orangespine Unicorn Fish (Naso lituratus)
  • Orbicular Batfish (Platax orbicularis)
  • Owens Pupfish (Cyprinodon radiosus)
  • Orbicular Velvetfish (Caracanthus typicus)


The O-lettered fishes are also a bulky class. In this group, you’d see fish of different colors and sizes. If you have not started your aquarium yet, you can browse through our five top O-lettered fishes and make a choice for yourself.

Kelly Stanley