Glass bloodfin

The glass bloodfin tetra (Prionobrama filigera) is a subtly beautiful South American characin distinguished by its semi-transparent body and brilliant red-orange caudal fin — a striking contrast that gives the species both its common name and its visual appeal. Native to the Amazon River drainage across Ecuador, Colombia, Peru, Bolivia, and Brazil, this active, pelagic species inhabits smaller streams, creeks, and tributaries where it forms schools near the upper water layers. It grows to around 6 cm in length and exhibits a slightly compressed, keeled body shape with an upturned mouth adapted for picking small invertebrates from the water surface.

Despite being somewhat underappreciated in the hobby, the glass bloodfin is an excellent choice for beginners. It is unfussy regarding water chemistry, accepts a wide variety of foods (particularly fond of live and frozen Daphnia, bloodworm, and Cyclops, but readily taking high-quality dried alternatives), and is robust when maintained under stable conditions. Males may engage in harmless squabbling over hierarchy, but the species is otherwise peaceful and makes an ideal tankmate for other similarly-sized South American species including Corydoras, smaller Loricariid catfish, Apistogramma dwarf cichlids, and Mikrogeophagus rams. They are naturally skittish and should always be kept in groups of at least 6–8 specimens.

An aquarium of 70–80 liters with dimensions of 60 × 37.5 cm or larger is adequate for a small school. The tank should contain plenty of open swimming space with some patches of floating vegetation to provide shade and security. Driftwood twigs, dried leaf litter, and a dark substrate help create a natural-looking set-up that encourages the fish to display their best coloration. Recommended water parameters include a temperature of 23–27°C, pH 6.0–7.5, and hardness up to 30°H. Breeding is achievable in a separate spawning tank with soft, acidic water and fine-leaved plants; eggs hatch within 14–36 hours and fry become free-swimming after 3–4 days.