Goby Lake that the diversity of species in the lake is greatly reduced from the nearby lagoon. The golden jellyfish "Mastigias" cf. "papua nakamurai" and possibly other species in the lake have evolved to be substantially different from their close relatives living in the nearby lagoons. The lake is rich with several species of fish, including goby, giving to lake its name. The deepest - north-eastern - part of Goby Lake is stratified into two layers, an oxygenated upper layer (mixolimnion) and a lower anoxic layer (monimolimnion). The oxygen concentration in the lake declines from about 6 mg/l at the surface to
Sand goby rounded. In males, there is a conspicuous dark spot on the anterior dorsal fin and in both sexes there is a black patch on the caudal peduncle. The general colour is sandy brown with indistinct dark blotches and reticulations on the dorsal surface and dark striations on the pale fins. The colour of the male darkens during the breeding season and his fins become more coloured. The average size is about . The sand goby normally lives at greater depths than the common goby. It feeds on small invertebrates living on the seabed especially amphipods. It is well camouflaged and