Not furry, but we like them anyway.
Rainbow Shark
Epalzeorhynchos frenatum
Also called Ruby shark, Red-fin shark, Rainbow sharkminnow, Green fringelip labeo, Whitefin shark
From Southeast Asia: the Mekong, Chao Phraya, Mae Klong and Xe Bangfai basins of Thailand, Laos and Cambodia.12
At a glance the quick version
Looks how to spot one
Slender bottom-dwelling minnow
A long, slim fish with a slightly downturned mouth. The wild form has a dark greenish-grey body set off by bright red fins. Males tend to be slimmer and more vivid, with dark lines edging the anal fin.123
Personality what they are like
Confident and strongly territorial, especially towards fish that look or behave like it. Usually best as the only one of its kind in the tank, with active mid- and upper-water tankmates chosen with care.23
Daily activity how busy a day looks
Active and always patrolling its patch of the tank bottom, so it needs floor space and lots of hiding spots.2
Grooming and care the hands-on bits
Keep a well-filtered tank with regular water changes. Water: about 20-27 C, pH 6.0-8.0, hardness about 2-15 dGH.21
Home where they are happiest
A tank of at least about 120 x 45 cm base (around 240 litres) for one fish, with rocks, wood and plants to break lines of sight. A lid helps as it can jump.21
Food basics what goes in the bowl
Mainly grazes on algae and the film on surfaces in the wild. In the aquarium give quality dried foods, vegetables and small live or frozen foods like bloodworm and brine shrimp.12
Company who they like around
A solitary fish; normally kept singly. If more than one is kept, each needs a large territory.2
The story where it all began
Henry Weed Fowler described the species in 1934, and it was later moved into the genus Epalzeorhynchos. It has been a long-standing favourite in home aquariums, where all stock is produced on farms.32
Fun facts for the dinner table
- 1
In the wet season it moves into flooded land, then returns to the river as the water drops.1
- 2
It is one of the species offered as genetically modified fluorescent GloFish.3
- 3
Although called a shark, it is a cyprinid, a relative of carp and minnows.3
- 4
With good care it may live for more than 15 years.2
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 2011).1
- Aquarium trade
- Aquarium fish are farm-bred; a genetically modified fluorescent version is sold under the GloFish brand.2
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Rainbow Shark. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
Owner questions the things everyone asks
How often should I feed my Rainbow Shark?
Feed your Rainbow Shark small amounts once or twice a day. Furry Diary's starting plan suggests daily feeding. Overfeeding can harm water quality, so stick to what it can eat in a couple of minutes.21 Furry Diary plan
What does a Rainbow Shark eat, and what should it never eat?
It mainly grazes on algae and biofilm, so offer quality dried foods, vegetables, and small live or frozen foods like bloodworm and brine shrimp. Avoid any foods that could spoil the water or are too large; for specific no‑go items, ask your vet or a good breeder.21
How much space does a Rainbow Shark need?
One Rainbow Shark needs a tank with a base of at least 120 x 45 cm (about 240 litres). It is active and patrols the bottom, so plenty of floor space with rocks, wood, and plants to break sight lines is important.21
What temperature, light or water does a Rainbow Shark need?
Keep the water between 20‑27°C, pH 6.0‑8.0, and hardness 2‑15 dGH. A well‑filtered tank with moderate lighting is fine; a lid helps because it can jump. Check temperature daily and test water weekly as part of your routine.21 Furry Diary plan
How often should I clean a Rainbow Shark's home?
Furry Diary's plan suggests a weekly 25% water change, cleaning the glass, and testing the water each week. Rinse the filter in old tank water (never tap water) once a month. Regular cleaning keeps your shark healthy. Furry Diary plan
Can a Rainbow Shark live with others?
It is strongly territorial, especially toward fish that look like it, so it is best kept alone or as the only one of its kind. If you want tankmates, choose active mid‑ and upper‑water fish and provide plenty of hiding spots. Each additional shark needs a very large territory.23
How long does a Rainbow Shark live?
With good care, a Rainbow Shark can live up to 15 years. Providing the right tank size, water quality, and diet will help it reach its full lifespan.2
Can I handle a Rainbow Shark?
Rainbow Sharks are fish and should not be handled. Handling causes stress and can damage their delicate slime coat. Enjoy watching them from outside the tank, and if you need to move one, use a soft net gently.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- FishBase: Epalzeorhynchos frenatum fishbase.seused for distribution, length, water, IUCN, diet, seasonal migration
- Seriously Fish: Epalzeorhynchos frenatum seriouslyfish.comused for care, tank, water, diet, behaviour, colour forms, lifespan
- Wikipedia: Rainbow shark en.wikipedia.orgused for other names, history, GloFish, colour forms
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.