Pristella tetra

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: plant safe.

Feeding

Eats anything. Flake, micro pellets, frozen bloodworm, frozen brine shrimp, frozen daphnia, live baby brine shrimp. Feeds in the midwater column. Not demanding, not competitive, not picky. A reliable feeder that will eat its share in any community. Twice daily in moderate amounts. Color in the fins improves with a varied diet that includes frozen food regularly. The yellow dorsal and anal fin markings are more vivid when the fish is well-fed and in good conditions.

Compatibility

• One of the most tolerant small tetras for varied water conditions. Pristella tetras handle hard alkaline water (up to pH 8, GH 20) without complaint, which makes them one of the few tetras suitable for keepers on hard tap water who don't want to run an RO unit.
• Peaceful schooling fish that works with any non-aggressive tankmate. Tetras, rasboras, corydoras, gouramis, and small cichlids are all fine. No nipping behavior.
• Groups of 6+ for proper schooling. In large groups (10+) the translucent body with yellow, black, and white fin markings is surprisingly attractive despite not having the flash of neons or cardinals.
• Also sold as the 'X-ray tetra' because the body is translucent enough to see the spinal column and swim bladder. The name oversells the transparency a bit but the effect is real under the right lighting.

Origin and habitat

Native to the Amazon and Orinoco basins and coastal river drainages across Venezuela, Guyana, Suriname, French Guiana, and northern Brazil. One of the broadest natural distributions of any popular aquarium tetra. The only member of its genus; Pristella is monotypic. Now placed in the family Acestrorhamphidae under the subfamily Pristellinae following a 2024 phylogenomic revision; older references list it under Characidae. Also called the X-ray tetra, pristella tetra, or water goldfinch. The translucent body makes internal bones and organs partially visible, inspiring the X-ray common name. Tricolor dorsal and anal fins with bands of yellow, black, and white; caudal fin red to pink. A golden color morph with enhanced yellow coloration is popular in the trade. Migrates seasonally: inhabits clearwater streams during the dry season and moves into flooded savannah to spawn when the rains come. Occurs in calm coastal waters and densely vegetated swamps; notably, one of the few tetras that tolerates slightly brackish conditions in freshwater-to-estuary habitats. Gregarious and non-aggressive. Grows to 4.5 cm total length. Lifespan typically 3-5 years in aquariums. Most trade specimens are commercially bred, not wild-caught.

Breeding

One of the more forgiving tetras to breed. Unlike many Amazon tetras, pristellas don't require ultra-soft acidic water. They'll spawn in moderately hard water (GH up to 15) that would prevent most Paracheirodon and Hyphessobrycon species from breeding. Condition a pair with frozen food for a week. Set up a breeding tank with fine-leaved plants or spawning mops, temperature at 25–27°C, and dim lighting. Spawning happens at dawn. The pair scatters 300-400 eggs among the plants. Eggs are non-adhesive and sink into plant material. Adults eat eggs, so remove them after spawning. Eggs hatch in 24-36 hours. Fry are tiny but not as small as neon tetra fry; they can take baby brine shrimp within 3-4 days of becoming free-swimming. Growth is steady. The tolerance for varied water conditions during breeding is the species' main advantage for hobbyist breeders.

Common problems

Hardy to the point of being boring. Serious health problems are rare. Ich appears in stressed new arrivals; standard treatment works. The species tolerates most medications without issue. The main 'problem' is cosmetic: pristella tetras look plain in poorly lit tanks with pale substrate. They need dark substrate, planted background, and warm-toned lighting to show their best. The fin markings wash out under cool white LEDs. This display-dependent attractiveness means they're consistently overlooked in store tanks, which is a shame because in the right setup they're one of the better schooling tetras available. Lifespan is 4-5 years. Old fish gradually lose fin color intensity.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size