Helfrich's Dartfish

About

Helfrich's dartfish (Nemateleotris helfrichi) is one of the more coveted small marines in the reef hobby, and for good reason. In the wild, this species inhabits steep seaward reef faces around French Polynesia, typically at depths well below the typical snorkeling zone. Think 40 meters and deeper. Out there, it hovers in pairs just above patches of sand, rubble, or exposed hard bottom, picking zooplankton from the water column. That monogamous pairing behavior translates nicely to the aquarium, where keeping a bonded pair often works out well. The fish is instantly recognizable by its pale lavender and yellow body and an impressively tall first dorsal fin that it flicks up and down almost constantly. Whether it's steadying itself in the current or signaling to nearby rivals, nobody's entirely sure, but it's striking to watch. Don't be fooled by its calm demeanor at the surface of the water column, though. This species is notably shy and will bolt for cover at the slightest disturbance, so a tank with plenty of caves and bolt-holes is essential. It's also territorial toward its own kind, so pairs work better than groups. A tight-fitting lid is a must. These fish are jumpers when stressed.