Ecology and behavior of tilefishes, Hoplolatilus starcki, H. fronticinctus and related species (Malacanthidae): non-mound and mound builders

Abstract

Observations on habitat and behavior are reported for 10 of the 12 known species of the genus Hoplolatilus. These small (6 to 20 cm total length) fishes are widespread in the tropical Indo-Pacific and Red Sea. Adults live as stable monogamous pairs and each pair shares a burrow. They feed on plankton during the day and retreat into a burrow to escape disturbances and to retire for the night. Usually the burrow location is inconspicuous, but 3 of the deeper water species build elaborate rubble mounds, to over 3 m in diameter, around their burrows. We studied the shallowest (13 to 61 m depth) species, H. starcki, that does not build mounds, and compared it with the shallowest (51 to 73+ m) mound builder H. fronticinctus. Over 60 pairs of H. starcki were studied. Ten-min observations (N=237) on 14 pairs were analyzed by time of day for feeding rates, courtship behavior, and distances of pairs in relation to each other and their burrows. Over 20 pairs of H. fronticinctus were studied by divers and on video from a remotely operated vehicle. These data showed a high rate of moving rubble (96.0 h-1), an activity almost absent in non-mound builders (0.1 h-1). Observations are also reported for non-mound builders H. chlupatyi, H. cuniculus, H. luteus, H. marcosi, H. oreni, H. purpureus, H. sp. (an undescribed species), and the mound builder H. pohle. The results of a survey of 159 dive sites with suitable habitats to over 25 m depth (including 49 dive sites over 50 m) indicate an abundance of Hoplolatilus species in the southwest Pacific. In comparison, 41 survey dive sites (including 20 over 50 m) in the Red Sea resulted in an unexplained absence of Hoplolatilus species except in deep water (>60 m). Mound builder, H. geo, is known in the north Red Sea (depths 80-116 m). H. fronticinctus, newly reported here, was found in the south Red Sea (depths 70-73 m). We also report, for the first time, live sightings of the rare H. oreni and H. sp. living unpaired and without mounds below 60 m in the south Red Sea. The wide distribution of H. fronticinctus, like the related Malacanthus brevirostris, suggests a possible advantage to building mounds even though mounds reveal the location of burrows. Recent techniques to extend scuba depths should increase our knowledge of the distribution of Hoplolatilus species.