An overview of the biology, reproductive techniques, and larval management of Cardinal Tetra (Paracheirodon axelrodi)

Abstract

The cardinal tetra (Paracheirodon axelrodi), a freshwater teleost within the order Characiformes, is predominantly to the Orinoco River basin of South America. It constitutes one of the most extensively imported ornamental species in the United States. Naturally,                P. axelrodi inhabits acidic blackwater environments characterized by low mineral content and lentic currents. Captive breeding is attainable through environmental manipulation, specifically by simulating rainfall and maintaining stringent physicochemical parameters: electrical conductivity (17–33 µS/cm), pH (5.1–5.9), dissolved oxygen (5.0 mg/L), and a stabilized temperature of 25–27 ^°C. The absolute fecundity of females ranges from 154 to 562 eggs per spawning event. The resulting embryos are spherical, transparent, and adhesive. Ontogeny progresses rapidly, with hatching occurring within 18–20 hours post-fertilization (hpf) and complete yolk-sac absorption within 5–6 days post-hatching (dph). During early ontogenesis, larvae are highly susceptible to pathogenic infections, often leading to elevated mortality rates. However, integrating dried Indian almond leaves (Terminalia catappa) into rearing systems optimizes water quality, mitigates physiological stress, and suppresses pathogen proliferation, thereby significantly enhancing larval survival. The objective of this study is to establish a comprehensive foundational database and a strategic research framework aimed at enhancing the commercial production potential of the cardinal tetra. This initiative seeks to facilitate import substitution and provide a sustainable pathway for socio-economic development within the ornamental aquaculture sector.