Latin Name: Gymnocorymbus ternetzi

Other Names: Black tetra, Black Skirt Tetra

How hard are they to keep? Black Widow Tetras are generally easy to keep, making them suitable for beginner aquarists. They are hardy and able to handle a variety of water conditions.

What is its maximum size? Black Widow Tetras can grow up to 2.5 inches (6.4 cm) in length.

Where are they from? Black Widow Tetras are native to the rivers and streams of South America, particularly in the basins of the Paraguay and Paraná rivers.

How many can I keep? Black Widow Tetras should be kept in groups of at least six individuals to thrive. They are schooling fish, and larger groups create a more natural and visually appealing display.

How compatible are they with other fish? Black Widow Tetras are generally peaceful but may exhibit fin-nipping behaviour, especially towards fish with long, flowing fins. They can coexist with other peaceful community fish, but caution should be taken when choosing tank mates. Compatible tank mates include other tetras, rasboras, and smaller peaceful species.

What are the ideal water conditions? Black Widow Tetras prefer slightly acidic to neutral water with a pH ranging from 6.5 to 7.5. The temperature should be maintained between 72°F to 79°F (22°C to 26°C). They are adaptable fish and can thrive in a variety of water conditions, but regular water changes and good filtration are recommended. The Black Widow Tetra that are for sale have been climatized to our local water conditions.

How do you tell the difference between male and female? Male Black Widow Tetras are usually slimmer and smaller than females. During breeding, males may exhibit a slight red coloration on their fins and body. Females, on the other hand, tend to have a rounder and fuller belly when they are carrying eggs.

Fun Fact: Despite its name and appearance, the black widow tetra is not harmful or aggressive like its arachnid namesake. These tetras are generally peaceful and can coexist with other fish in a community aquarium. The “black widow” label is due to the black coloration near the base of its tail fin, resembling the markings on the abdomen of a black widow spider. So, while the black widow tetra may look a bit menacing to some, it’s actually a friendly and fascinating addition to many aquariums.