Fish Profile: Sewellia Lineolata

S. Lineolata Adult near-surface.

Last night I introduced a new fish to you all as one of the occupants of my 55 Gallon tank. The tiger hillstream loach - properly known as Sewellia Lineolata - is a native of southern Vietnam and a riverine fish.

Squat and wide, with fanned pectoral and ventral fins, S. Lineolata reminds many of a ray in miniature - such a resemblance is superficial, and while there are a few species of freshwater ray (mostly Chinese , few are suited to the freshwater aquarium, or at least one so small as any I have ever owned or worked in.

S. Lineolata is actually a loach, though it is more commonly identified as a pleco, with which it bears no resemblance other than a superficial one, and a similarity in tank role. Beyond being striking enough that a small school of these would be an excellent feature in a tank (if not an expensive one), Lineolata is a fantastic grazer of awfuchs, including a few strains that common plecostomus won't touch, such as blue-green algae, or brown algae, which are actually bacteria and diatoms, respectively. Because of this diet, it is best to introduce them into a tank with advanced biofilm development - if this is impossible or undesirable, they can usually be persuaded to eat a sinking algae wafer such as those produced under the Wardly brand, but, as alway, the natural route is preferred.

These fish like to be kept in large groups of six or more only if sufficient territorial markers such as branches, dens, and large rocks are provided. They are domineering and exhibit some (usually harmless) violence between con-specifics and similarly-shaped fishes. For this reason (and matters of financial practicality) I keep only one. Ideally, one such fish would live in about ten gallons of water at a minimum.

A relatively new fish to the hobby (first appearing in the mid-2000s), these fish can be somewhat difficult to source. Locally, Pets Unlimited carries a small selection of them when they are available from our breeders, usually for around $21.97 a piece, depending on what we paid for them. Their newness to the hobby makes them a little more finicky than more veteran species, and the best success is found in imitating their natural conditions.

Those conditions are fairly predictable based on their location - overfiltration (tank turnover of 15-20 per hour), 68-78 degrees Farenheit, soft water at about 6.0-7.5 pH.