Siamese algae eater
Crossocheilus oblongus
A slim silver fish with a black stripe and one of the few that eats black beard algae; grows to about 6 inches and loves to jump.
Key facts
- Body length
- 5.9 in without fins
- Minimum tank
- 95 gallons
- Group
- Alone is fine
- Temperament
- Peaceful
- Care level
- 1 / 5
- Lifespan
- 10+ years
- Diet
- Algae, algae wafers, vegetables, flakes
- Origin
- Chao Phraya and Mekong basins and the Malay Peninsula
- Hardier than53%
- Bigger than73%
- Calmer than68%
Water: their range vs yours
Siamese algae eater tank mates
- Neon tetraGets along in shared water.Good mates
- Harlequin rasboraGets along in shared water.Good mates
- Fancy guppyGets along in shared water.Good mates
- Panda corydorasGets along in shared water.Good mates
- Cherry shrimpGets along in shared water.Good mates
- BettaGets along in shared water.Good mates
- AngelfishGets along in shared water.Good mates
- Tiger barbGets along in shared water.Good mates
- Amano shrimpGets along in shared water.Good mates
- Black neon tetraGets along in shared water.Good mates
- Black widow tetraGets along in shared water.Good mates
- Bristlenose plecoGets along in shared water.Good mates
- OtocinclusSiamese algae eater outcompetes the slow-eating Otocinclus for food; target-feed to make sure it eats.Risky
- Blood parrot cichlidSiamese algae eater outcompetes the slow-eating Blood parrot cichlid for food; target-feed to make sure it eats.Risky
- Blue dolphin cichlidBlue dolphin cichlid can eat young or small Siamese algae eater; adults are big enough to be safe.Risky
- Chinese algae eaterChinese algae eater attacks fish with a similar shape or colour: Siamese algae eater.Risky
- Clown loachClown loach attacks fish with a similar shape or colour: Siamese algae eater.Risky
- Convict cichlidConvict cichlid (aggressive) will bully the peaceful Siamese algae eater.Risky
- Iridescent sharkIridescent shark can eat Siamese algae eater: prey body depth 2.6 cm ≤ mouth 32.5 cm.Avoid
- OscarOscar can eat Siamese algae eater: prey body depth 2.6 cm ≤ mouth 12.3 cm.Avoid
- Rainbow sharkAttacks lookalike algae eaters.Avoid
- Red-tailed black sharkAttacks lookalike algae eaters.Avoid
- African clawed frogAfrican clawed frog should only be kept in a single-species tank.Avoid
- Marbled crayfishMarbled crayfish should only be kept in a single-species tank.Avoid
How we check
The numbers the tank model uses for Siamese algae eaters: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 15 cm (TL)
- Adult mass
- 31.42 g
- Bioload at 25 °C
- 9.10 BU
- Min. water
- 304 L net
- Min. footprint
- 150 × 45 cm per group
- Group
- 1+ (best 6)
- Swims in
- bottom, middle
- Flow
- moderate
- Body / fins
- fusiform, normal fins
- Diet type
- algivore
- Fin nipper
- none
- Sensitive to
- —
Sources: FishBase: Crossocheilus oblongus · Wikipedia: Siamese algae-eater · Seriously Fish: Crossocheilus (genus) · sera: Siamese Algae Eater
Care notes
Siamese algae eaters come from clear, fast hill streams and rapids of the Chao Phraya, Mekong and Malay Peninsula. Several similar species are sold under this name, and the true fish is easy to confuse with the Chinese algae eater or the sharks.
Give them a roomy tank, ideally around 75 gallons with a 5-foot footprint, and a tight lid. Young fish graze black beard algae, but adults often switch to regular food, and some fish may nibble java moss.
Questions
What size tank does a siamese algae eater need?
At least 95 gallons (304 litres of water after decor). Adults reach about 5.9 inches without fins.
How many Siamese algae eaters should be kept together?
One is fine. They do not need company of their own kind.
What water do Siamese algae eaters need?
75–79 °F, pH 6.5–8 and 5–20 dGH. Siamese algae eaters come from Chao Phraya and Mekong basins and the Malay Peninsula.
How long do Siamese algae eaters live?
10+ years with good care.
What fish can live with Siamese algae eaters?
Good tank mates include Neon tetra, Harlequin rasbora, Fancy guppy, Panda corydoras and Cherry shrimp. Each is checked both ways for size, fin nipping, temperament, territory and shared water.