Three-lined Corydoras

Three-lined Corydoras key facts

Care level

Beginner-friendly

Lifespan

4-7 years

Size

5.5-6.1cm

Temperature

22〜26℃

Diet

Sinking dried foods, frozen bloodworm, Tubifex

Tank

A 45 x 30cm base, about 41 litres, is the practical minimum and FishBase likewise recommends a tank of at least 60cm. Use fine rounded sand and never block access to the surface.

Water Temperature & Quality

22-26C, pH 5.8-7.2, 1-12dGH. FishBase records 22-26C, pH 6.0-8.0 and 5-19dH in the wild.

Tank Mates

Peaceful and gregarious, and FishBase recommends keeping five or more. It mixes well with peaceful small and medium-sized fishes.

Diet & Feeding

A foraging omnivore. Offer sinking dried food plus frozen bloodworm and Tubifex. It must never be expected to live on leftovers or to clean the tank.

Breeding & Spawning

Use two males per female. Once females are gravid, make a 50-70 percent water change with cooler water and raise oxygenation and flow. Eggs are laid on glass, fine-leaved plants or spawning mops.

Health & Notes

Assessed Least Concern by the IUCN Red List. It is readily confused with Hoplisoma julii, and fish labelled julii are usually this species.

About Three-lined Corydoras

Corydoras trilineatus, known for its speckled body and maze-like head pattern, is a calm, beginner-friendly bottom-dwelling catfish often sold as "Julii."

7 things to know before welcoming a Three-lined Corydoras

1. 1Often Sold as "Julii"

   Fish sold under the trade name "Julii" are, in many cases, actually this species rather than the true Corydoras julii. Because the two look similar, it helps to check the distinctive dark flank band and the maze-like head pattern before buying.

2. 2Thrives in Groups

   Corydoras are naturally social and tend to school together. Keeping several individuals in the same tank reduces shyness and hiding, making it easier to enjoy their active, curious behavior on the tank floor.

3. 3Soft Substrate Matters

   This species constantly sifts through the substrate while foraging, using its sensitive barbels to search for food. Sharp or coarse gravel can irritate or wear down these barbels, so a fine, rounded sand substrate lets it forage naturally and comfortably.

4. 4Good Community Fish

   Peaceful and non-aggressive, this fish pairs well with other small, similarly sized species. Because it spends most of its time near the substrate, it rarely competes for space with fish that occupy the mid- or upper-water levels.

5. 5Sensitive to Sudden Changes

   Like most Corydoras species, this fish can be sensitive to abrupt shifts in water parameters or temperature. Acclimate it slowly when introducing it to a new tank, and favor small, frequent water changes over large, infrequent ones to keep it settled.

6. 6Watch for Signs of Low Oxygen

   Corydoras can breathe air at the surface using intestinal respiration, so occasional trips to the surface are normal. If this behavior becomes unusually frequent, however, it can signal low dissolved oxygen, making it a useful cue to check aeration.

7. 7Cycle the Tank Before Arrival

   Even though this species is considered beginner-friendly, a freshly set-up tank tends to have unstable water conditions. Letting the filter's nitrogen cycle establish itself before adding fish helps create an environment where the Corydoras is less likely to develop health issues.

Frequently asked questions about Three-lined Corydoras

Q.How big does Corydoras trilineatus grow?

A.It typically reaches about 5.5 to 6.1 cm (2.2 to 2.4 inches) as an adult, making it a compact species that suits relatively small tanks.

Q.Is this species suitable for beginners?

A.Yes, it's generally considered beginner-friendly. That said, it's sensitive to sudden changes in water quality, so regular partial water changes and careful acclimation are recommended.

Q.Is this the same fish sold as "Julii"?

A.Many fish sold under the trade name "Julii" are actually this species. It closely resembles a related species in pattern, which is why the two are often confused in the trade.

Q.Can it be kept with other fish?

A.Yes, it's peaceful and pairs well with other small, similarly sized fish. Since it stays mainly near the bottom, it rarely conflicts over territory with mid- or upper-level swimmers.

Q.Is this species subject to CITES?

A.Corydoras trilineatus is not subject to CITES.

Useful tools for Three-lined Corydoras care

Learn more about Three-lined Corydoras in the encyclopedia

More in this category