Black Widow Tetra Care Guide
Gymnocorymbus ternetzi · Freshwater Fish
What Black Widow Tetra look like
The Black Widow Tetra, Gymnocorymbus ternetzi, exhibits a deep, laterally compressed body that can reach a maximum adult size of approximately 5 inches (12.7 cm). This species is characterized by its striking silver coloration adorned with two prominent vertical black bands located on the anterior half of the body, providing a stark contrast that enhances its visual appeal. The anal fin is particularly notable, being intensely black and significantly wider than that of closely related species, which aids in identification. Sexual dimorphism is subtle, with females generally appearing slightly fuller-bodied than males, especially when gravid. Defensive adaptations include a schooling behavior that provides safety in numbers, as well as the ability to quickly dart away from potential threats. The presence of a lateral line system allows for enhanced detection of water movements, further aiding in predator avoidance.
Behavior & temperament
Gymnocorymbus ternetzi is a social fish that thrives in groups, exhibiting a strong tendency to form schools in the mid to upper water column of its habitat. This species is generally peaceful but can display territorial behavior, particularly during breeding periods. Breeding occurs through egg scattering, where females release eggs in open water, allowing males to fertilize them externally. The Black Widow Tetra is known for its active swimming patterns and can often be seen darting about in the aquarium, showcasing its lively temperament. While it is not aggressive, it may exhibit mild fin-nipping behavior if kept in overly crowded conditions or with long-finned tank mates.
Diet & feeding
In the wild, the Black Widow Tetra is an omnivore, feeding on a varied diet that includes small invertebrates, plant matter, and detritus. In captivity, it requires a balanced diet consisting of high-quality flake foods, supplemented with live or frozen foods such as brine shrimp and daphnia to ensure optimal health and coloration.
Behind the name
The genus name Gymnocorymbus is derived from the Greek words 'gymnos' (naked) and 'corymbus' (cluster), referring to the nakedness of the body without scales in certain areas. The species name ternetzi honors the German zoologist, Dr. Karl Ternetz.
Plan your tank
Check the numbers before you buy: tank volume, a stocking plan, cycle progress, water changes, and your ongoing care routine.
Keeping Black Widow Tetra?
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