Catfish & plecos · Hoplisoma trilineatum

Julii corydoras care guide

Also called: Julii cory, False julii cory, Three-lined cory, Three-stripe corydoras, Trilineatus cory, Corydoras trilineatus

The julii corydoras sold in shops is almost always the three-lined cory (Hoplisoma trilineatum, formerly Corydoras trilineatus), a peaceful spotted catfish with a dark stripe along its side. It is easy to keep in a group of 6 or more on soft sand.

Julii corydoras need a tank of at least 20 gallons (76 L), a group of 6 or more, and water at 22–26°C (72–79°F) with a pH of 6–7.5. They grow to about 5.5 cm (2.2 in) and are peaceful.

Plan a tank with julii corydorasSee all tank mates

Julii corydoras quick facts

Scientific nameHoplisoma trilineatum
FamilyCallichthyidae
OriginAmazon basin in Peru, Colombia and Brazil, plus coastal rivers of Suriname (the true C. julii is from north-eastern Brazil and rarely sold)
Adult size5.5 cm (2.2 in)
Minimum tank20 gallons (76 L), at least 60 cm (24 in) long
Temperature22–26°C (72–79°F)
pH6–7.5
Hardness (GH)2–12 dGH
Group size6 or more (shoaling fish)
TemperamentPeaceful
Swims atBottom
DietOmnivore
Care levelEasy
Lifespan5–10 years
Safe with shrimp?Mostly (eats baby shrimp)
Safe with plants?Yes
  • Needs sand or smooth, fine gravel to protect its barbels and belly.

Tank setup

A group of 6 needs at least 20 gallons (76 L) with a floor at least 24 in (60 cm) long. Use fine sand and add plants, wood and shady spots where the group can rest. Keep the water well oxygenated with moderate flow, and leave an air gap under the lid.

How many julii corydoras in a tank?

The smallest common tank that suits julii corydoras is a 20 gallon. Here is roughly how many fit in each size when they are the only fish, based on adult size and waste output. Leave room if you want tank mates.

TankJulii corydoras (alone)
3 gallonToo small
5 gallonToo small
10 gallonToo small
15 gallonToo small
20 gallon6–16
20 gallon long6–16
29 gallon6–24
40 gallon6–33
55 gallon6–46
75 gallon6–63
125 gallon6–105

What you need for julii corydoras

Sized for a 20 gallon tank, the smallest common size that suits a group of 6 julii corydoras. For a different tank or a mix of fish, use the stocking calculator for a list sized to your plan.

Tank and equipment

Food and extras for julii corydoras

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Water parameters

Aim for 22–26 °C (72–79 °F), pH 6.0–7.5 and 2–12 dGH. They do best in the cooler to middle part of the tropical range rather than in very warm tanks. Weekly 25–30% water changes keep nitrate low, which protects their barbels.

Best tank mates for julii corydoras

These popular species share julii corydoras' water needs and temperament. See the full list of 95 good matches.

Avoid keeping julii corydoras with

  • Oscar: Oscar can eat julii corydoras: they're small enough to fit in its mouth once it's grown.
  • Chinese algae eater: Chinese algae eater is aggressive and will bully or injure peaceful julii corydoras.
  • Convict cichlid: Convict cichlid is aggressive and will bully or injure peaceful julii corydoras.
  • Discus: They need different temperatures: Julii corydoras 22–26°C (72–79°F), discus 28–30°C (82–86°F).
  • Electric yellow cichlid: Electric yellow cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Julii corydoras don't belong in that setup.
  • German blue ram: They need different temperatures: Julii corydoras 22–26°C (72–79°F), german blue ram 27–30°C (81–86°F).

Feeding

Feed sinking pellets or wafers daily and add frozen or live bloodworm, brine shrimp or daphnia a few times a week. They forage across the whole floor, so spread the food out if you keep a big group. They need their own food, not just leftovers.

Behavior

Peaceful and fairly active, they spend the day sifting sand in a loose group and are much bolder with others of their kind. Small tetras, rasboras, pencilfish, dwarf cichlids and other calm fish make good companions, and open-swimming midwater fish help them feel safe. Avoid large or aggressive fish.

Breeding

Like most corys, they spawn after a big, slightly cooler water change, usually in a group with about two males per female. The female carries a few eggs at a time between her pelvic fins and sticks them to glass, plants or decor. The adults eat eggs, so move them; they hatch in about 3–5 days and the fry take microworms or baby brine shrimp.

Tips from experienced keepers

  • Shops label this fish julii, but it is almost always C. trilineatus. Care is the same, so the mix-up does not affect your tank.
  • True julii have small dots on the head; trilineatus have a maze-like pattern and a bolder side stripe.
  • Keep 6 or more of the same species. A mix of single corys will not shoal as well.
  • Avoid sharp gravel and dirty substrate, which wear down their barbels.
  • Add calm midwater fish. Corys come out more when they see other fish swimming openly.

Frequently asked questions

What is the difference between julii and three-lined corydoras?

The true julii cory has fine spots on its head and is rarely exported. The three-lined cory has a more maze-like pattern and a bolder side stripe, and it is the fish most shops sell as julii.

How many julii corydoras should be kept together?

Keep at least 6 of the same species. They shoal loosely and are more active and confident in a bigger group.

How big do julii corydoras get?

Most grow to about 2–2.25 in (5–6 cm). Females are slightly larger and rounder than males.

What is the scientific name of the julii cory?

Most shop fish are Corydoras trilineatus, which recent research moved to the genus Hoplisoma as Hoplisoma trilineatum. The rare true julii is now Hoplisoma julii.

Sources

We checked these references when writing this page. Values are for healthy long-term keeping, not survival limits. Last reviewed 2026-10-13. See our editorial policy.