Will these sightless fish fit in?

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Are Blind cave tetras suitable for a general community? A reader asks for Neale’s advice…

Q) Please can you tell me whether Blind cave tetras are suitable for a general community? It’s a 120x44x44cm set-up with Platies, a solitary Angel, Bronze and Skunk corys, Harlequins and Silvertip tetras. The tank has been set up for 12 months with very few problems, save for the unexplained death of the other Angel. Will Blind cave tetras fit in? I’ve heard reports of them being fin nippers, although I’m not sure how that’s possible when they can’t see. Also, how can I make sure they get enough to eat?

NEIL WEARING, VIA EMAIL

A) Neale responds: While the Blind cave tetra is a hardy and adaptable fish, it’s not a perfect community tank resident. Unlike the South American tetras, this Mexican species comes from a limestone environment and prefers moderately hard water with a neutral to slightly basic pH. Living in caves as it does, it also experiences lower water temperatures than its South American relatives, with around 22-24˚C being ideal.

The word ‘restless’ doesn’t begin to describe its behaviour, and in fact, it seems to navigate by sensing changes in the pressure waves created as it swims along. In the wild the fish feeds on bat droppings, which oddly enough contain a lot of undigested insect remains. Needless to say, it’s not a picky eater!

Even so, it doesn’t always compete well with other fish at feeding time, and tankmates shouldn’t be too boisterous. Conversely, it’s approach to finding food is very much ‘bite and see what happens’ and this isn’t helpful when the fish is kept with slow-moving species like Guppies, gouramis, and, unfortunately, Angels.

On the other hand, if the Angel and the Blind cave tetra rarely meet, any such experimental bites will be infrequent. In a large tank, you might combine them with success, particularly if your Angel isn’t one of the long-finned strains. But being blind fish, night and day are the same thing to these tetras, and where an Angel might avoid the fish easily enough during the daytime, at night, when it is asleep, it could be at more risk. So, it’s hard to say for sure whether the combination would work.