Arrow Loach

About

The Arrow Loach (Nemacheilus masyai) is a small but feisty loach from the rivers and streams of western Malaysia and Peninsular Thailand, with populations also recorded from the Meklong and parts of the Mae Nam Chao Phraya drainages. In the wild it favors shallow, moderately flowing water over muddy and sandy substrates, turning up in both clear, slightly tannin-stained forest streams and more turbid conditions. Identification is fairly straightforward once you know what to look for: 14 to 18 short dark vertical bars along each flank, a series of saddle markings running down the back, a dark spot at the end of the lateral line on the caudal peduncle, and a dark blotch in the lower portion of the front dorsal-fin rays. The body is noticeably more slender than the closely related N. pallidus, and the dark bars tend to be wider than the pale spaces between them, sometimes merging together. Despite being listed as a beginner-friendly species overall, this fish earns its territorial reputation and can be rough with similarly shaped loaches. Interestingly, it is peaceful toward its own kind, and keeping a group of four or more actually seems to settle individuals down. Pairing them with open-water cyprinids and rheophilic bottom dwellers tends to work well, though mixing them with other Nemacheilus or Schistura species calls for a close eye and a roomy setup.