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Axelrodia riesei
Axelrodia riesei, commonly known as the Tetra Ruby, is a small and strikingly colored freshwater fish species that originates from South America. This popular aquarium fish is cherished for its distinctive red and white markings and vibrant schooling behavior.
Habitat and Range
In the wild, Tetra Rubies are believed to inhabit blackwater environments, but detailed information is lacking. It is presumed that they prefer smaller, forested tributaries rather than larger river channels. These fish are typically found in slow-moving, blackwater streams in the Amazon River basin and its tributaries in South America. They are often found among submerged vegetation and root systems and prefer soft, acidic water conditions.
Maximum Standard Length
The maximum standard length of Tetra Rubies is typically in the range of 15 to 20 mm.
Aquarium Size
Despite their small size, it is recommended to provide a minimum aquarium size with base dimensions of 60 x 30 cm or equivalent for long-term care. Smaller aquaria can be used for breeding purposes.
Maintenance
Tetra Rubies are best maintained in a well-structured set-up, ideally comprising a sandy substrate, driftwood roots, and branches. Adding dried leaf litter can enhance the natural feel of the aquarium and provide additional cover for the fish. It also encourages the growth of microbe colonies as decomposition occurs, offering a valuable secondary food source for fry. The tannins and other chemicals released by decaying leaves are considered beneficial for fish from blackwater environments. Alder cones may also be used for this purpose. This species thrives under fairly dim lighting, and compatible aquatic plant species like Microsorum, Taxiphyllum, or Cryptocoryne spp. can be added. Floating vegetation, especially Ceratopteris spp., is also useful.
Water Conditions
- Temperature: 20 – 28 °C - pH: 4.0 – 6.5 - Hardness: 18 – 90 ppm
Diet
Tetra Rubies are likely micropredators feeding on tiny invertebrates and other zooplankton in their natural habitat. In the aquarium, they readily accept dried foods of a suitably small size but should also be offered daily meals of small live and frozen fare such as Artemia nauplii, Daphnia, Moina, grindal worm, etc.
Behavior and Compatibility
Tetra Rubies are peaceful with other species but may not be ideal for a community fish tank due to their small size and somewhat specialized requirements. Ideally, they should be maintained alone or with diminutive, non-aggressive characids, and smaller callichthyid or loricariid catfish. Although gregarious by nature, they are a shoaling rather than schooling species, with rival males forming small territories and sparring on a regular basis. A minimum purchase of 8-10 specimens is recommended to reduce shyness and promote interesting behavior.
Sexual Dimorphism
Adult males are slightly smaller and more intensely colored than females. Sexually mature females appear rounder-bodied than males, especially when gravid. It's unclear whether the differences in color pattern in newly-imported wild fish relate to gender or not.
