Larval nurseryfish, Kurtus gulliveri (Perciformes: Kurtidae), in the Adelaide River of the Northern Territory: Their season, fellow travellers and unusual rib anatomy

This study was undertaken to determine the spawning season of the nurseryfish, a species with a unique method of parental care found only in northern Australia and southern New Guinea. Monthly samplings with an ichthyoplankton net at the same locality in the Adelaide River over multiple years yielded no larval nurseryfish in February, March, April and May. Larvae first appeared in June and were collected each month until January. From this we conclude that the nurseryfish spawning season in the Adelaide River is June-January. Twelve other larval fish species from 10 families were collected in the plankton tows with nurseryfish. Larval nurseryfish are readily identified and separated from other larval fishes by their peculiar rib anatomy, an important diagnostic character of Kurtus. The development of the unusual rib anatomy is examined with three-dimensional micro-computerised tomography scans of 12-21-mm standard length (SL) specimens. The bony protection of the swim bladder formed by the ribs is visible in the smallest postflexion specimens examined and is essentially complete by 19mm SL. These ecological and anatomical observations add another pixel to the big picture of nurseryfish life history.