Vertical Orientation in a New Gobioid Fish from New Britain

WHILE VISITING Rabaul, New Britain, during Cruise 6 of the Stanford University vessel "Te Vega" we observed and collected specimens of a small gobioid fish that swam and hovered vertically, with its head up, in midwater close to pockets in the wall of an underwater cliff at depths below 30 feet. Many kinds of fishes, for example scorpaenids and cottoids, are known to orient vertically in contact with a substrate. There are fewer examples of vertically oriented fishes in midwater; among the best known are the seahorses and centriscids. Observations have also been made on vertically oriented mesopelagic fishes. Barham (1966) has seen myctophids hovering vertically, as well as swimming upward and downward. Paralepidids are also known to be vertical swimmers (Peres, 1958; Bernard, 1958; Cohen, personal observations). We have found, however, no previous record of this habit in gobioid fishes and our observations are presented herewith. We have been unable to identify the fish with any known form, and we describe it as a new species in the genus Trimma.