81+ Outstanding Fish Names that Start with O [ Fish Names ]

Are you a fish enthusiast looking for new additions to your aquarium? Look no further! In this comprehensive guide, we have compiled a list of 25 fish names that start with the letter “O”. From freshwater to saltwater species, there is something for every type of fish keeper. So let’s dive in and explore these fascinating fish!

1. Oscar

The Oscar, also known as astronotus ocellatus, is a popular freshwater fish native to South America. They are characterized by their vibrant colors and distinct personalities. Oscars can grow up to 18 inches long and require a large tank with plenty of hiding spots. These omnivorous fish are quite hardy and can live up to 10 years with proper care.

2. Ocean Sunfish

Also known as Mola mola, the ocean sunfish is an unusual-looking fish found in temperate and tropical waters worldwide. They are known for their flattened body shape, which gives them a unique appearance. Despite their size (they can reach up to 11 feet in length), ocean sunfish are docile and gentle creatures, making them a popular attraction in aquariums.

3. Ocellaris Clownfish

Commonly known as Nemo, the ocellaris clownfish is a small saltwater fish found in the Indo-Pacific region. They have distinct orange and white stripes and form symbiotic relationships with anemones in the wild. These popular fish have been bred in captivity and are a great addition to beginner saltwater tanks.

4. Orange Chromide

The orange chromide, also known as etroplus maculatus, is a small cichlid native to India and Sri Lanka. They are characterized by their bright orange coloration and are a peaceful species suitable for community aquariums. These fish prefer planted tanks with warm water and can live up to 5 years in captivity.

5. Oranda Goldfish

The oranda goldfish is a popular freshwater fish known for its distinctive head growth called the wen. They come in various colors, including orange, red, black, and white. Orandas are hardy fish that can live up to 15 years with proper care. They do well in tanks with plenty of swimming space and a varied diet.

6. Oyster Toadfish

Found along the Atlantic coast of North America, the oyster toadfish is a unique-looking saltwater species known for its bulging eyes and large mouth. They are bottom-dwelling fish that can camouflage themselves with their surroundings, making them difficult to spot in the wild. Oyster toadfish are not recommended for beginner fish keepers due to their aggressive nature.

7. Opaline Gourami

The opaline gourami is a peaceful freshwater fish native to South Asia. They have a distinct blue-green coloration and are characterized by their long, flowing fins. Opaline gouramis do well in community aquariums with plenty of hiding spots and can live up to 4 years in captivity.

8. Orange Spotted Filefish

The orange spotted filefish, also known as oxymonacanthus longirostris, is a reef-safe saltwater fish found in the Indo-Pacific region. They have a unique body shape and are known for their ability to change color to blend with their surroundings. These fish should only be kept by experienced aquarists as they require a specific diet and can be difficult to keep in captivity.

9. Orinoco Peacock Bass

The orinoco peacock bass is a large freshwater fish found in the Orinoco River basin in South America. These predatory fish are popular among sport fishers due to their aggressive nature and impressive size (they can reach up to 3 feet long). They require a spacious tank with plenty of hiding spots and should only be kept by experienced aquarium hobbyists.

10. Ornate Bichir

The ornate bichir, also known as polypterus ornatipinnis, is a fascinating freshwater fish found in parts of Africa. They have a unique appearance with elongated bodies and fleshy dorsal fins. Ornate bichirs are carnivorous and can live up to 20 years in captivity with proper care.

11. Orange-Finned Anemonefish

The orange-finned anemonefish, also known as amphiprion chrysopterus, is a small saltwater fish found in the Indian and Pacific Oceans. They have a vibrant orange coloration and form symbiotic relationships with anemones in the wild. These hardy fish are suitable for beginner saltwater tanks and can live up to 10 years in captivity.

12. Orange-Finned Barb

The orange-finned barb is a peaceful freshwater fish found in Southeast Asia. They have a striking coloration with bright orange fins and black spots on their body. These active swimmers do well in community tanks with other peaceful species and are relatively easy to care for.

13. Oceania Blue-Eye

The oceania blue-eye, also known as pseudomugil cyanodorsalis, is a small and colorful freshwater fish found in the rivers and streams of Papua New Guinea. They have vibrant blue stripes on their body and striking red eyes. Oceania blue-eyes are peaceful fish that do well in planted tanks and can live up to 3 years in captivity.

14. Olive Sea Snake

The olive sea snake, also known as aipysurus laevis, is a venomous saltwater species found in the Indian and Pacific Oceans. They have a unique olive green coloration and are active swimmers. These elusive snakes should only be kept by experienced aquarists as they require specialized care and can be dangerous if mishandled.

15. Orange-Spotted Goby

The orange-spotted goby, also known as amblygobius albimaculosus, is a small saltwater fish found in the Western Pacific region. They have a distinctive body shape with an elongated dorsal fin and bright orange spots. These fish are peaceful and do well in reef tanks with plenty of hiding spots.

16. Oyster Blenny

The oyster blenny, also known as osticola cyanosoma, is a small saltwater fish found along the east coast of Africa. They have an elongated body shape and are known for their unique coloration that resembles oyster shells. Oyster blennies are peaceful and do well in tanks with plenty of hiding spots and an established sand bed.

17. Orange-Spotted Shrimp Goby

The orange-spotted shrimp goby, also known as amblyeleotris guttata, is a small saltwater fish found in the Western Pacific region. They have an elongated body with bright orange spots and are known for their symbiotic relationship with shrimp. These peaceful fish should be kept in pairs and do well in reef tanks.

18. Oyster Plant Goby

The oyster plant goby, also known as cryptocentrus leptocephalus, is a small saltwater fish found in the Western Pacific region. They have a unique body shape with an elongated dorsal fin and are known for their ability to camouflage themselves with their surroundings. Oyster plant gobies do well in reef tanks and require a diet rich in meaty foods.

19. Orange-Finned Danio

The orange-finned danio, also known as devario devario, is a peaceful freshwater fish found in South Asia. They have a striking appearance with bright orange fins and black stripes on their body. These active swimmers do well in schools and are relatively easy to care for.

20. Octopus

The octopus is a fascinating saltwater creature found throughout the world’s oceans. They have eight arms, three hearts, and highly developed brains, making them highly intelligent animals. Due to their specialized care requirements and potentially aggressive nature, octopuses should only be kept by experienced aquarists in a species-only tank.

21. Orange Spotted Sleeper Goby

The orange spotted sleeper goby, also known as valenciennea puellaris, is a peaceful saltwater fish found in the Indo-Pacific region. They have a unique appearance with dark spots on an orange body and are known for their ability to burrow in the substrate. These fish do well in reef tanks and require a diet rich in meaty foods.

22. Orangespine Unicornfish

The orangespine unicornfish, also known as naso lituratus, is a reef-safe saltwater fish found in the Indian and Pacific Oceans. They have a distinctive body shape with long spines on their dorsal fin and are known for their ability to graze on algae. These peaceful fish do well in large tanks with plenty of swimming space.

23. Orange Blenny

The orange blenny, also known as salarias fasciatus, is a peaceful saltwater fish found in the Eastern Pacific region. They have a unique appearance with yellow and orange stripes on their body and are known for their ability to eat hair algae. These hardy fish do well in tanks with plenty of live rock and hiding spots.

24. Oriental Weatherfish

The oriental weatherfish, also known as misgurnus anguillicaudatus, is a peaceful freshwater fish found in East Asia. They have an eel-like appearance and are known for their ability to survive in a wide range of water conditions. These hardy fish do well in community tanks and can tolerate colder temperatures than most tropical fish.

25. Otocinclus Catfish

The otocinclus catfish, also known as otocinclus affinis, is a peaceful freshwater fish found in South America. They have a unique appearance with an elongated body and are known for their ability to eat algae. These social fish do well in groups and require a well-maintained tank with plenty of hiding spots.

More Fish Names Starting with Letter O:

S.No	Fish Name	Description
1	Ocean Sunfish	The heaviest known bony fish in the world, known for its unique shape.
2	Ocellaris Clownfish	Known as the “Nemo” fish, it’s a small, brightly colored species popular in aquariums.
3	Octopus Squid	A deep-sea species that shares characteristics with both octopuses and squids.
4	Olive Flounder	A flat, bottom-dwelling fish found in the Pacific Ocean.
5	Opah	A large, deep-sea fish known for its round body and vibrant coloration.
6	Oranda Goldfish	A popular aquarium fish known for its prominent bubble-like “hood”.
7	Oscar Fish	A large, intelligent freshwater fish popular in aquariums.
8	Oyster Toadfish	A bottom-dwelling marine fish known for its ugly appearance.
9	Old Wife	A reef fish known for its black and white stripes and venomous spines.
10	Orange Roughy	A deep-sea fish known for its bright orange skin and long lifespan.
11	Oriental Flying Gurnard	Known for its large, wing-like pectoral fins.
12	Ornate Butterflyfish	A brightly colored reef fish known for its intricate patterns.
13	Ornate Ghost Pipefish	A small, delicate fish that resembles seaweed.
14	Ornate Wobbegong	A bottom-dwelling shark known for its ornate camouflage pattern.
15	Orfe	A type of goldfish known for its elongated body and high speed.
16	Olive Barb	A freshwater fish native to Asia, known for its olive color.
17	Otomebora Mudskipper	A species of mudskipper found in Asia.
18	Ocellated Waspfish	A small, venomous fish found in the Indo-Pacific region.
19	Ozark Cavefish	A small, blind fish that lives in caves in the United States.
20	Odessa Barb	A small, brightly colored freshwater fish native to Asia.
21	Orange Chromide	A small cichlid native to India and Sri Lanka.
22	Orange Sea Cucumber	Not a fish but a marine animal with a soft body and leathery skin.
23	Owlfish	A deep-sea fish known for its large eyes and bioluminescent organs.
24	Owens Pupfish	A small fish native to California, it’s one of the rarest fish in the world.
25	One-Spot Puller	A small, colorful reef fish found in the Indian and Pacific Oceans.
26	Orange-Spotted Blenny	A small, bottom-dwelling fish known for its orange spots.
27	Ornate Cowfish	A small, boxy fish known for its horns and ornate patterns.
28	Oval-spot Butterflyfish	A small, tropical fish known for the oval spot on its side.
29	Onyx Clownfish	A variety of clownfish known for its dark, almost black coloration.
30	Oblique-Banded Sweetlips	A reef fish known for its thick lips and oblique bands.
31	Oceanic Puffer	A large, round fish that can inflate its body when threatened.
32	Olive Danio	A small, fast-swimming freshwater fish native to Southeast Asia.
33	Oriental Loach	A small, bottom-dwelling freshwater fish native to Asia.
34	Orange-Spotted Filefish	A small, tropical fish known for its ability to change color.
35	Orange-Spotted Goby	A small, bottom-dwelling fish known for its bright orange spots.
36	Oarfish	The longest bony fish in the world, known for its slender, ribbon-like body.
37	Opaleye	A small, silver-gray fish found along the Pacific coast of North America.
38	Oceanic Whitetip Shark	A large, pelagic shark known for its rounded white-tipped fins.
39	Orangespine Unicornfish	A reef fish known for its orange spines and horn-like projection.
40	Olive Ridley Sea Turtle	Not a fish but a marine reptile, known for its mass nesting events.
41	Oxeye Oreodory	A deep-sea fish known for its large, round eyes.
42	One-Lined Rainbowfish	A small, brightly colored freshwater fish native to Australia.
43	Okinawa Goby	A small, bottom-dwelling fish native to the waters around Okinawa, Japan.
44	Orange Sea Pen	Not a fish but a type of coral, named for its pen-like shape.
45	Oscar Cichlid	A large, aggressive freshwater fish popular in aquariums.
46	Ochre Starfish	Not a fish but a marine animal, known for its five arms and rough skin.
47	Olive Rockfish	A bottom-dwelling marine fish found along the Pacific coast of North America.
48	Olive Greenling	A small, bottom-dwelling fish found in the northeastern Pacific Ocean.
49	Orange Clownfish	A small, brightly colored reef fish, also known as the clown anemonefish.
50	Oni Chrysopa	A species of ray-finned fish in the family Nemipteridae.
51	Oriental Sweetlips	A large, tropical fish known for its striking black and white stripes.
52	Orange Filefish	A small, brightly colored fish known for its ability to change color.
53	Ozark Bass	A small freshwater fish found in the Ozark region of the United States.
54	Okinawa Goby	A small, bottom-dwelling fish native to Okinawa, Japan.
55	Onyx Clownfish	A variety of clownfish known for its dark, almost black coloration.
56	Oblique Swimming Anemone	Not a fish but a type of marine animal that uses its tentacles for locomotion.
57	Ornate Sleeper Ray	A type of electric ray known for its ornate patterns.
58	Ocean Perch	A deep-sea fish known for its bright red color.
59	Olive Snipe Eel	A deep-sea fish with an elongated body and beak-like jaws.
60	One-Spot Foxface	A colorful reef fish known for its fox-like face and single spot.

Conclusion:

Overall, these 85 fish names that start with “O” showcase the diversity and beauty of aquatic life. From colorful freshwater fish to venomous saltwater species, there is something for every type of aquarist. Remember to always do thorough research before adding any new fish to your tank, and happy fishing!