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I'm considering adding a school of Congo tetras to one of my tanks, but I'm getting mixed signals on their ideal water conditions. Some sources claim they're an African species, requiring hard water, which seems unusual for a tetra. Others insist that, being a tetra, they naturally prefer soft water.

My best guess is to aim for neutral water, assuming they inhabit a river rather than a rift lake. I figure the water would've started out hard from its source, but then been influenced by the surrounding vegetation, which probably softened it to some extent. thoughts???

I strongly advise against paying attention to any site that claims Congo Tetras require hard water - it's a clear indication of their unreliability.

What I do suggest is creating a list of trustworthy sources and sticking to them. Many of us rely on Seriously Fish, which is an excellent comprehensive database for hobbyists. Other notable sites include CorydorasWorld, Planet Catfish, and Loaches Online, each specializing in specific fish. A common trait among these reliable sites is their tendency to agree on data, which is rooted in scientific evidence rather than baseless claims.

Regarding the water conditions for Congo Tetras, Phenacogrammus interruptus, let's set the record straight. The African rift lakes are unique, boasting the highest GH water among the fish species we keep in aquaria. The cichlid fauna in these lakes is a prime example of rapid evolution, resulting in diverse yet closely-related species. However, this is not relevant to Congo Tetras, as they inhabit a different environment.

In reality, tropical Africa, much like South America and SE Asia, is characterized by very soft, slightly acidic water. Congo Tetras thrive in such conditions, specifically in the calm waters of streams and rivers in the Congo River basin. The ideal water parameters for this species are soft to medium hard (4-18 dGH), acidic to slightly basic (pH 6-7.5, but ideally below 7), and temperatures between 23-27C/73-80F. To keep them happy, you'll need a 4-foot tank with a minimum group of 10-12 individuals. They're quite entertaining, often engaging in what I call "relay races," where two males swim side by side from one end of the tank to the other.