Psalidodon anisitsi

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Psalidodon anisitsi, also known as the Buenos Aires tetra, is a hardy, active South American characid that is especially accessible to aquarists. Its silvery body, highlighted by red-orange fins, brings constant movement to a freshwater community aquarium. This schooling species benefits from the company of several conspecifics and usually adapts well to soft to moderately alkaline water. Its reputation as a hardy fish explains its popularity, while its lively behavior and reasonable adult size suit spacious freshwater aquariums. It should nevertheless be provided with adequate swimming length and efficient filtration. A stable group and varied diet help maintain both its natural behavior and coloration.

General species description

Psalidodon anisitsi is a small schooling fish in the family Characidae, native to eastern and southern South America. It mainly inhabits lowland waterways, calm tributaries and areas with aquatic or overhanging vegetation. In an aquarium, it should be kept in a suitably sized group to encourage natural behavior and reduce nervousness. It is an energetic swimmer that mainly uses the middle level of the aquarium. Although usually peaceful, it may occasionally nip the fins of very slow or delicate fish when kept in too small a group. This species is very common in the aquarium trade and adapts well to a range of freshwater layouts and conditions.

Geographical origin and biotope

Reference countries: Argentina, Brazil and Paraguay. Psalidodon anisitsi is associated with the Paraná and Uruguay drainage systems, including lowland streams, side channels and marginal areas with slow to moderate flow. The biotope generally includes clear to slightly tea-colored water, a bottom of sand, gravel or mud, and plant debris gathered along the banks. Emergent and submerged vegetation provides shelter, while open areas allow the school to move freely. In an aquarium, well-oxygenated water, regular circulation and shaded areas reproduce these conditions more effectively than a completely open layout.

Precise locality and local name

Within its South American range, Psalidodon anisitsi is mainly associated with the Río Paraná drainage and connected areas of the Río Uruguay basin. The most widespread aquarium name is Buenos Aires tetra, referring to the Buenos Aires region and the species’ long commercial history. In several Spanish-speaking countries, the generic term mojarra may also be used for small characids, although it does not refer exclusively to this species. For accurate identification, the scientific name Psalidodon anisitsi remains the most precise reference.

Appearance and physical characteristics

Psalidodon anisitsi has a streamlined, relatively deep body covered with silvery scales. A darker coloration may be visible along the back, while the anal, pelvic and caudal fins often show red-orange tones. The caudal fin is usually more vivid in well-conditioned adults. Mature females are often deeper-bodied and rounder than males, especially when carrying eggs. Males tend to be more slender. The maximum adult size is approximately 7 cm, although many aquarium specimens remain smaller. Clean water, a varied diet and a stable school help promote stronger coloration and better overall condition.

General diet

As an opportunistic omnivore, Psalidodon anisitsi readily accepts quality commercial foods. Flakes, micro-pellets and small floating or slowly sinking foods can form the dietary base. To support condition and coloration, small frozen or live foods such as brine shrimp, daphnia and mosquito larvae should be offered regularly. Portions should remain modest and be eaten quickly to protect water quality. A varied diet given in small meals supports growth and natural behavior more effectively than relying on one food every day. Plant matter and organic material found in the habitat also contribute to its natural feeding pattern.

Essential data

• Name of native river: Río Paraná and Río Uruguay drainage system
• Local name used: Mojarra; Buenos Aires tetra
• Origin of the scientific name: Psalidodon is the genus name; anisitsi is the specific epithet
• Complete name etymology: Psalidodon approximately means scissor-toothed; anisitsi honors Anisits
• Common/vernacular names: Buenos Aires tetra, Tetra Buenos Aires
• Family: Characidae
• Subfamily: Stethaprioninae
• Name pronunciation: sal-i-do-don an-i-see-tsi
• Discovery: Carl H. Eigenmann, 1907
• Maximum adult size: About 7 cm
• Water temperature and pH: 18 to 28 °C; pH 6.0 to 8.0
• Waterway appearance and surrounding vegetation: Lowland waterways, vegetated margins, organic debris and shaded areas
• Typical tankmates: Gymnocorymbus ternetzi, Pristella maxillaris, Hoplisoma paleatus
• Temperament and behavior: Active, schooling and generally peaceful; mainly swims in open water
• Water depth: Shallow to moderate, in marginal areas and lowland tributaries
• Sexual dimorphism: Females are rounder; males are usually more slender
• Bottom structure and flow: Sand, gravel or mud; slow to moderate current

In your aquarium

Success with Psalidodon anisitsi begins with an aquarium offering ample swimming length, stable water and an appropriately sized school. A layout combining plants, roots and open areas allows the fish to feel secure while remaining active. Use efficient filtration without creating excessive current, and avoid tankmates that are extremely slow or have fragile fins. Moderate temperatures, regular water changes and a varied diet help preserve health and coloration. Under these conditions, this common tetra is an excellent choice for a lively community aquarium.