Whiptail catfish

The twig or whiptail catfish is a slender, stick-shaped loricariid from the Orinoco drainage of Colombia and Venezuela, where it clings to submerged branches and roots in clear, flowing streams. A note on the name: most 'Farlowella acus' in the hobby are in fact F. vittata — true F. acus is rarely, if ever, exported — but the two are near-identical in care and are traded interchangeably. Whichever you have, it is an olive-brown fish with a dark side stripe and a long needle snout, so well camouflaged that it disappears against wood. It grows to about 15 cm.

Everything about this fish comes back to one point: it is a delicate grazer that starves easily. It eats aufwuchs and algae, so it belongs only in a mature, established tank with a good film of algae and biofilm already growing, backed up with algae wafers, spirulina and blanched vegetables such as courgette and spinach. It is also very sensitive to water quality and to being moved, so it needs stable parameters, gentle drip acclimation and clean water with near-zero nitrate.

Give it an 81 litre tank, reasonably long, with fine sand, vertical driftwood and hardy plants such as Anubias and Java fern. Keep the flow well-oxygenated but not turbulent, at 24–27 °C, pH 6.0–7.0, in soft water. It is entirely peaceful and does well in a quiet community of small tetras, rasboras and corydoras, and it is content in a small group — several can share a tank, though rival males posture a little. In good conditions it is long-lived, up to fifteen years or so. Males guard the eggs, which are laid on a cleaned vertical surface and hatch in about a week.