Last Updated: October 17, 2026
No true shark can be kept in a normal home aquarium, and the freshwater “sharks” sold in shops are actually minnow-family fish (the red tail black shark, rainbow shark, bala shark) and the Siamese algae eater, which only resemble sharks; of these, the rainbow shark, red tail black shark and Siamese algae eater are the realistic home choices, while the bala shark needs a huge tank when full grown. All of them need more planning than their cheap juvenile price suggests.
Quick answer: Our top pick in 2026 is the Red tail black shark (Epalzeorhynchos bicolor) — our #1 rated choice. See the full ranked comparison, alternatives and buying advice below.
Freshwater “Sharks” at a Glance
| Fish | Adult size (Seriously Fish) | Minimum tank | Temperament | Realistic for a home tank? |
|---|---|---|---|---|
| Red tail black shark (Epalzeorhynchos bicolor) | About 12.5 cm (5 in) standard length | 120 x 45 cm base, about 243 litres (64 US gal) | Increasingly territorial with age; best kept singly | Yes, with a large tank and careful tank mates |
| Rainbow shark (Epalzeorhynchos frenatum) | About 15 cm (6 in) | 120 x 45 cm base, about 243 litres (64 US gal) | Increasingly territorial; aggressive to similar-looking fish | Yes, as a single fish in a large tank |
| Bala shark (Balantiocheilos melanopterus) | About 35 cm (14 in) | 240 x 60 cm base, about 864 litres, for a group of adults | Peaceful but huge, active, and a shoaler | Rarely; needs a very large tank |
| Siamese algae eater (Crossocheilus species) | 3-6 in depending on species (about 7.5-15 cm) | From 120 x 30 cm for the smaller species (C. atrilimes) to 150 x 45 cm for the larger (C. langei) | Shoaling; Seriously Fish recommends a group of at least six | Yes, in the right tank and group |
What “Freshwater Shark” Really Means
The word “shark” is a trade name. Red tail black sharks and rainbow sharks belong to the same carp and minnow family (cyprinids) as barbs and danios. Their high dorsal fin and torpedo shape give them a shark-like silhouette, but they have bony skeletons, breathe through gills like any other aquarium fish, and are not related to marine sharks. Calling them “sharks” does not describe their temperament either, because they are usually shy until they claim a territory.
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View on AmazonYoung fish are sold at a few centimetres and look harmless, which is a recurring problem in the trade. Juveniles are often sold with little information about their eventual size, temperament or longevity, which is a common reason these fish end up being rehomed.
Red Tail Black Shark
The red tail black shark has a velvet-black body and a bright red tail. Seriously Fish gives a maximum standard length of about 12.5 cm and a minimum tank base of 120 x 45 cm, roughly 243 litres. The profile describes the species as increasingly territorial with age, particularly toward similar-looking fish, and says that although it is normally sold as a community fish it is largely unsuitable for the general community aquarium. It is best kept singly. Seriously Fish gives a lifespan of over 15 years and describes it as needing a well-established tank with stable water conditions.
Water preferences are 20-26 C, pH 6.0-8.0 and 2-15 dGH, with high dissolved oxygen and moderate flow. It grazes on algae and biofilm but also needs supplementary foods such as frozen bloodworm, daphnia and brine shrimp, plus vegetables such as peas and cucumber. Seriously Fish also notes it is critically endangered in the wild (once declared extinct and later rediscovered) and that aquarium fish are commercially farm-bred.
Rainbow Shark
The rainbow shark is a similar fish with a dark body and red fins. Seriously Fish lists a maximum length of about 15 cm, a minimum base of 120 x 45 cm (about 243 litres) for a single specimen, a lifespan of more than 15 years, and a temperature range of 20-26 C with pH 6.5-8.0. It becomes increasingly territorial as it grows, with aggression toward similar-looking fish, so one per tank is the usual advice. Small specimens tend to hide much of the time, but keepers report that the fish chases others from the bottom and territorial skirmishes get worse with age.
Bala Shark
The bala shark, or silver shark, is a shoaling fish and by far the largest of the group. Seriously Fish gives 35 cm as its maximum standard length and says the smallest acceptable aquarium for a group of adults has a base of 240 x 60 cm, around 864 litres. Seriously Fish says it should always be kept in a group of five or more, and it is listed as endangered by the IUCN because wild populations have dwindled. It is mostly peaceful but eats very small fish and tends to disturb timid tank mates with constant activity. It needs strong water flow with filter turnover of 8-12 times per hour. For most homes, this makes the bala shark a poor match: a juvenile in a 100-litre tank has nowhere to go as it grows, and keepers who cannot provide the space often struggle to rehome it.
Siamese Algae Eater
The Siamese algae eater is not a shark but is often sold alongside sharks as a cleanup fish. Seriously Fish describes several Crossocheilus species: the smaller C. atrilimes reaches about 7.5 cm and needs a 120 x 30 cm tank, while the larger C. langei reaches about 15 cm and needs 150 x 45 cm. Both prefer 20-26 C and pH 6.0-7.5, and the profiles recommend groups of at least six. The trade name “Crossocheilus siamensis” is not valid, and several species are sold under it. The flying fox (Epalzeorhynchos) is a different genus, and fish sold as “false flying fox” or “Siamese flying fox” add to the confusion. Because identity is muddled in the trade, check the fish before buying, and do not assume one will quietly clean a whole aquarium. Algae eating also does not solve the underlying cause of an algae outbreak, which is usually light and nutrients.
Compatibility: Good, Risky and Avoid
| Tank mate | With red tail or rainbow shark | Why |
|---|---|---|
| Medium-sized, fast mid-water fish (larger danios, barbs, rasboras) in a long tank | Good | They occupy different zones and can outswim chasing |
| Corydoras and other peaceful bottom fish | Risky | Bottom space is the shark’s territory; works only in a big, well-decorated tank |
| Another rainbow or red tail shark | Avoid | Aggression toward similar-looking fish |
| Other long-bodied dark bottom dwellers (some loaches, plecos) | Avoid or risky | May be seen as rivals |
| Slow, long-finned fish and bettas | Avoid | May be harassed |
| Very small fish, fry and shrimp | Avoid with bala sharks, risky with others | Bala sharks eat small fish |
Why True Sharks Are Unsuitable
True sharks are marine animals (a few species enter river water, but none are suited to home tanks). Even the smaller sharks sold for aquariums, such as some bamboo sharks and catsharks, are long-lived, grow large and need very big saltwater systems with tight water quality and specialised care. Keepers who plan for a “pet shark” typically underestimate the swimming space, volume, filtration, feeding and cost required over a lifespan of many years. Legal restrictions on some species also apply, so check local rules. If the goal is a shark look, one of the freshwater fish above, or other fish that simply look like sharks, is the more responsible route, and a public aquarium visit is the better way to see actual sharks.
Choosing: A Decision Table
| Pick this if… | Choice |
|---|---|
| You have a tank of roughly 240 litres or more and want one bottom-level character fish | One rainbow or red tail shark |
| You have a large tank (about 864 litres or more) and want an active school | A group of bala sharks, with large tank mates |
| You want a small algae-grazing fish for a moderate tank and can keep a group | Siamese algae eaters (six or more) |
| You have a small or community tank under 200 litres | Skip the sharks and choose smaller peaceful fish |
| You want a real shark | Visit a public aquarium; do not attempt a home tank |
Set-Up and Care Checklist
- Size the tank for the adult. Use the Seriously Fish minimums in the table above, not the juvenile’s current size.
- Cycle the tank first. These fish do best in a mature, stable system with plenty of oxygen and moderate current.
- Add hiding places. Caves, driftwood and plants break sightlines and give a territorial fish somewhere to retreat.
- Add the shark last or first? Many keepers introduce territorial fish late, after other fish have settled, so the shark does not claim the whole tank, though this does not guarantee peace.
- Feed a mixed diet. Provide algae wafers or vegetables with live or frozen foods, as Seriously Fish suggests.
- Plan for years. Rainbow and red tail sharks can pass 15 years, so someone must be willing to care for them that long.
Troubleshooting
| Symptom | Likely cause | Fix |
|---|---|---|
| Shark chasing other bottom fish | Territory defence | Add cover, rearrange decor, remove one fish if needed |
| Torn fins on tank mates | Shark attacks | Rehome the shark or the victim; do not wait |
| Fish hiding all day | Bullying, bright open tank or poor water | Add shelter, test water, review tank mates |
| Bala sharks darting and crashing into glass | Tank too small or group too small | Move to a larger tank and a group of five or more |
| Algae returning despite algae eaters | Excess light or nutrients | Reduce light and feeding, increase water changes |
Frequently Asked Questions
Can you keep a real shark in a home aquarium?
No. True sharks are marine animals that need very large saltwater systems with specialised care. Even small species grow larger and live longer than most keepers can accommodate.
What is the best freshwater shark for a home aquarium?
The rainbow shark and red tail black shark are the most practical, kept singly in a tank of around 240 litres or more. The Siamese algae eater suits a smaller tank, but it needs a group of six or more.
How big do freshwater sharks get?
According to Seriously Fish, red tail black sharks reach about 12.5 cm, rainbow sharks about 15 cm and bala sharks about 35 cm. Siamese algae eaters range from about 7.5 to 15 cm depending on species.
Can I keep two rainbow sharks together?
Usually it is a bad idea. They become increasingly territorial and aggressive toward similar-looking fish, so one per tank is the common advice.
Are bala sharks good for community tanks?
Only in very large tanks. They are peaceful but grow to about 35 cm, need strong flow and groups of five or more, and eat very small fish.
Do freshwater sharks eat algae?
They graze on algae and biofilm but need other foods too, and they will not remove a heavy algae problem on their own. Fixing light and nutrient balance is the real answer.
How long do rainbow and red tail sharks live?
Seriously Fish reports lifespans of over 15 years for both, so they are a long-term commitment.
Ready to decide? Our #1 pick for 2026 is the Red tail black shark (Epalzeorhynchos bicolor).
Live price & availability on Amazon.
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