Can Blind Cave Tetra and True Julii Corydoras Live Together?

Possible with Caution

Keeping Blind Cave Tetra and True Julii Corydoras together is possible but requires caution due to differing aggression levels. Provide a spacious tank of at least 110 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

Blind Cave Tetra

Astyanax mexicanus

True Julii Corydoras

Corydoras julii

🐠Family Group
Blind Cave Tetra
Characins
True Julii Corydoras
Catfish
Temperament
Blind Cave Tetra
Mostly Peaceful (4/10)
True Julii Corydoras
Peaceful (0/10)
Temperature
✓ Compatible
Blind Cave Tetra
20–25°C
True Julii Corydoras
23–26°C
pH Range
✓ Compatible
Blind Cave Tetra
6.5–8
True Julii Corydoras
6–7.5
Hardness (dGH)
✓ Compatible
Blind Cave Tetra
8–20
True Julii Corydoras
2–15
Water Type
✓ Compatible
Blind Cave Tetra
Freshwater Only
True Julii Corydoras
Freshwater Only
Flow Preference
✓ Compatible
Blind Cave Tetra
Moderate
True Julii Corydoras
Moderate
Min Tank Volume
Combined: 110 L
Blind Cave Tetra
110 L
True Julii Corydoras
60 L
Swimming Level
Shared: 1 zone
Blind Cave Tetra
MiddleBottom
True Julii Corydoras
Bottom
🏷️Behavior Tags
Blind Cave Tetra
Hyperactive / Fast SwimmerFin NipperAggressive Eater (Starves shy fish)
True Julii Corydoras
Hyperactive / Fast Swimmer
Stocking calculator

Can your tank handle Blind Cave Tetra and True Julii Corydoras?

Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.

Blind Cave Tetra
True Julii Corydoras
Test both in my tank

Behaviour & Temperament

Blind Cave Tetra is a generally mild-mannered species (4/10), while True Julii Corydoras is peaceful (0/10). This notable difference means Blind Cave Tetra may occasionally assert dominance over True Julii Corydoras.

Blind Cave Tetra and True Julii Corydoras both frequent the Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat. Keep fin nippers in larger groups to distribute nipping behaviour among conspecifics rather than tank mates.

Water Parameters

The safe temperature window for both species falls between 23°C and 25°C. Aim for the midpoint of this range (around 24.0°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 8–15 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Blind Cave Tetra and True Julii Corydoras together, plan for an aquarium of at least 110 litres with a minimum length of 80 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Smooth Gravel (Sensitive Barbels), Sand (Sifters). Meeting these requirements will help both species thrive.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Suitable Tank Sizes

Standard aquarium sizes large enough for both Blind Cave Tetra and True Julii Corydoras.

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Frequently Asked Questions

Can Blind Cave Tetra and True Julii Corydoras live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 110 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do Blind Cave Tetra and True Julii Corydoras need?

A minimum of 110 litres (tank length at least 80 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.

What water temperature is best for Blind Cave Tetra and True Julii Corydoras together?

Keep the aquarium between 23°C and 25°C. A target of around 24.0°C sits comfortably within both species' preferred ranges.

Are Blind Cave Tetra or True Julii Corydoras aggressive?

Blind Cave Tetra is generally mild-mannered (4/10) and True Julii Corydoras is peaceful (0/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Blind Cave Tetra and True Julii Corydoras need?

Both species overlap in the 6.5–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Will Blind Cave Tetra nip True Julii Corydoras's fins?

Blind Cave Tetra is a known fin nipper. If True Julii Corydoras has long or flowing fins, there is a real risk of fin damage. Keeping Blind Cave Tetra in a larger group can help redirect nipping behaviour toward conspecifics.


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