What fish can live with Cardinal Tetra?

Usually safer companions on this hub include Corydoras Catfish, Dwarf Gourami, Harlequin Rasbora. Open each pair check before you buy — the list is a shortlist, not a guarantee.

What tank mates should you avoid with Cardinal Tetra?

Avoid Jack Dempsey, Oscar based on size, temperament, or predation risk on this profile.

What size tank do Cardinal Tetra need for a community?

75L+ is realistic. The school needs lateral length to spread, and the extra volume buffers the parameter swings cardinals do not tolerate.

Cardinal Tetra tank mates

Cardinal tank mates live or die on water chemistry before temperament charts. Soft, warm, mature water comes first; then filter anything with a mouth that fits a 5 cm tetra. Angels and rams can work in the right soft-water show tank; hard-water livebearers and cool-water danios fight the cardinal's needs even when everyone is 'peaceful.' Build the school to eight or more so they hold midwater instead of vanishing into the stems.

Common mistakeKeeping small cardinal groups in hard or bright water is how keepers invent faded fish that 'never looked like the shop.' They need soft, dimmer conditions and a real school. Token numbers in a hard community kit are the wrong ownership plan.

Evidence: verified

Confidence: high

Each name below opens a pair check with Cardinal Tetra. That check is the decision, not the list itself.

← Full Cardinal Tetra profile·Compatibility checker·Tank builder·More tetra

Usually safer companions

Conservative shortlist from this profile. Open a pair page before you buy.

Corydoras Catfish Pair check
The Cardinal Tetra profile lists Corydoras Catfish as both safe and a recommended pairing. Corydoras Catfish schools in groups of 6 or more, so plan room for the whole group rather than one fish. Corydoras Catfish swims in the bottom zone while Cardinal Tetra stays in the middle, so the two will not crowd the same water column.
Dwarf Gourami Pair check
The Cardinal Tetra profile lists Dwarf Gourami as both safe and a recommended pairing. Dwarf Gourami is a peaceful beginner-care species with a 60L minimum. Run the pair checker for your specific tank before stocking.
Harlequin Rasbora Pair check
The Cardinal Tetra profile lists Harlequin Rasbora as both safe and a recommended pairing. Harlequin Rasbora schools in groups of 6 or more, so plan room for the whole group rather than one fish.

Risky or situational

May work with more water, a mature system, or a species-only setup. Read the pair page before you experiment.

Angelfish Open pair check
Angelfish reaches 20cm and is flagged predatory or as likely to eat small fish. Adult-size Cardinal Tetra at 5cm is inside that gape range. Angelfish is rated semi-aggressive, so expect chasing, fin damage, or display behaviour directed at Cardinal Tetra. Run the pair checker before stocking.
Tiger Barb Open pair check
Tiger Barb is rated semi-aggressive, so expect chasing, fin damage, or display behaviour directed at Cardinal Tetra. Run the pair checker before stocking.

Fish to avoid with Cardinal Tetra

Predation, aggression, or space rules on this profile. Treat these as poor default mixes.

Jack Dempsey See why (pair)
Jack Dempsey reaches 25cm and is flagged predatory. Cardinal Tetra at 5cm is prey-sized for it. Jack Dempsey needs at least 200L, far above the 60L minimum for Cardinal Tetra. The tank that houses one stresses the other. Jack Dempsey is rated aggressive and Cardinal Tetra is rated peaceful. No community-style planning carries that gap.
Oscar See why (pair)
Oscar reaches 35cm and is flagged predatory. Cardinal Tetra at 5cm is prey-sized for it. Oscar needs at least 300L, far above the 60L minimum for Cardinal Tetra. The tank that houses one stresses the other. Oscar is rated aggressive and Cardinal Tetra is rated peaceful. No community-style planning carries that gap.

Tank size and groups

Published minimum for Cardinal Tetra: 60L. Group minimum 6 (schooling).
Compatibility changes when the tank is too short for turning, too little for a real school, or too warm for one species and not the other. That is why pair checks include tank context, not only temperament.
Nearest litre hub to this minimum: 60L hub.

Plan before you buy

Start a pair check with Cardinal Tetra, or open a starter plan with the top safer companions in the builder.

Open pair checker Open this plan in builder

Tank hubs: 60L

Filtration & heating

A 60L minimum tank for Cardinal Tetra needs a filter rated for at least 240L/hr turnover and a heater maintaining 23–27°C.

Filter size guide →Heater size guide →Tank setup checklist →Beginner plants guide →

Related (care + temperament)

Other species that list Cardinal Tetra

Reverse lookup: these profiles reference Cardinal Tetra under safe or “best with” lists.

Featured compatibility checks

Curated pair pages for Cardinal Tetra. Each opens a full verdict — not just a list label.