What size tank does a Blind Cave Tetra need?

Blind Cave Tetra needs a minimum of 20 gallons, with 30 gallons recommended. They are middle swimmers. Keep in groups of 5+.

Is Blind Cave Tetra good for beginners?

Blind Cave Tetra is rated "beginner" difficulty (1/5). Great for beginners.

What fish are compatible with Blind Cave Tetra?

Blind Cave Tetra is semi-aggressive. Compatible tank mates include other semi-aggressive fish with similar water parameters (pH 6.5-8, temp 68-82°F). Give adequate territory space.

Blind Cave Tetra

Astyanax mexicanus

Family: Characidae • Origin: Various

Blind Cave Tetra (Astyanax mexicanus) is a semi-aggressive tetra reaching 4.5 inches. Keep in groups of 5+. Minimum tank: 20 gallons.

Min Tank

20 gal

Max Size

4.5"

Temperature

68-82°F

6.5-8

Lifespan

7 years

School Size

Swim Level

middle

Hardness

5-15 dGH

semi-aggressivebeginneromnivoreschooling

Is Blind Cave Tetra Right for Your Tank?

Blind Cave Tetra is an excellent choice for beginners — rated "beginner" difficulty (1/5). They're hardy, forgiving of minor water parameter fluctuations, and generally easy to feed. A 20-gallon tank minimum is standard — most community setups will accommodate them.

Blind Cave Tetra is semi-aggressive — they can live with others but may bully smaller or slower fish. Choose tank mates carefully. This is a schooling species — keep at least 5 together, or they may become stressed and display abnormal behavior. They are territorial — provide adequate hiding spots and maintain enough space to reduce aggression. Expected lifespan: 7 years with proper care.

Common Mistakes with Blind Cave Tetra

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Keeping fewer than 5 together

Blind Cave Tetra is a schooling species — they need a group of at least 5 to feel secure. Lone or paired individuals become stressed, hide constantly, and may develop health issues or aggression.

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Relying on a heater without a thermometer

Blind Cave Tetra needs 68–82°F. Heaters malfunction or drift over time — always use a separate thermometer to verify. Temperature swings of even 3–4°F can trigger stress and disease, particularly ich.

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Putting them in a tank under 20 gallons

Many beginners underestimate tank size needs. Blind Cave Tetra requires at least 20 gallons — ideally 30. Cramped tanks lead to stunted growth, aggression, and poor water quality.

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Housing with peaceful nano fish

Blind Cave Tetra is semi-aggressive and territorial — small, peaceful species like neon tetras, endlers, or celestial pearl danios will be stressed, bullied, or eaten. Choose tank mates that can hold their own.