Three-Line Corydoras

Corydoras trilineatus

Also known as: False julii cory, Three-stripe cory, Trilineatus cory

Water Parameters

• Temperature: 22–26°C
• pH: 6–7.5
• Hardness (GH): 36–214 ppm (2–12 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

One of the most commonly-sold spotted corydoras, almost always under the name 'julii cory' even though the genuine Corydoras julii seldom reaches the trade, the three-line cory is a small, hardy, finely-patterned catfish marked with a network of dark spots and a stripe along the flank. It has everything that makes corydoras a community staple: it is peaceful, sociable, endlessly busy sifting the substrate, and undemanding once given the soft floor and the group of its own kind that every cory needs. A school of them working over the bottom of a planted tank is constant gentle activity, and they make excellent clean-up companions for a wide range of community fish. Hardy, attractive, and long-lived, the three-line cory is a reliable and rewarding choice, just sold under a slightly misleading name.

Tankmates

A peaceful schooling catfish that must be kept in a group of at least six on soft sand or smooth rounded gravel to protect its barbels, like all corydoras. Frequently sold as the 'julii cory', though the true Corydoras julii is rarely imported and most fish under that name are actually this species; the two look almost identical (fine spots and a reticulated head) and their care is the same. Peaceful and too small to threaten any tankmate, it is safe with the smallest community fish and adult shrimp (it may eat eggs and the tiniest shrimplets), and it pairs well with tetras, rasboras, peaceful gouramis, and dwarf cichlids. Avoid large or aggressive tankmates that will harass or eat it.

Compatible with

• Neon Tetra
• Harlequin Rasbora
• Ember Tetra
• Glowlight Tetra
• Pristella Tetra
• Honey Gourami
• Cherry Shrimp
• Betta

Avoid keeping with

• Large Cichlids
• Oscar
• Convict Cichlid
• Fin Nippers
• Aggressive Tankmates

Common Problems

• damaged barbels from sharp substrate
• stress in groups smaller than 6
• ich
• being sold under the wrong name (julii) which can confuse care research

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20