two-thirds of the long of the first knuckles of an adult. Adult fish can have a maximum length of about six centimeters (2.3 inch). Compared to other herrings, they are very small (the length of Clupea harengus adult fish is up to 45 cm long) which is why they lack self-preservation in the face of other fish. The auditory and visual system Inferred from Actinopterygii, the glassy sprat's auditory system is otoliths (Ladich & Popper, 2004). From the ancestral state deduced from Osteichthyes, the glassy sprat's eye lens can be described as spherical with increasing optical density towards the centre (Land & Fernald, 1992). The mineralized tissue of its otolith contains aragonite. Habits Glassy sprat are diurnal, often gathering in large numbers and appearing in groups. Their primary food is unprotected small underwater insects and plankton. They mainly live in shallow salty and brackish waters with seagrass growing up to 50 meters, including the Great Barrier Reef World Heritage Area and Marine Park, Moreton Bay Marine Park, the Great Sandy Marine Park, and the Jervis Bay Marine Park. Of the 52 fish species that can be caught in the seagrass area of sea area East Australia, Glassy sprat has the highest fish density. Distribution This fish belongs to the Australian characteristics of fish species, mainly in two states, Queensland and New South Wales and they often live in brackish water area closer to the mainland. They are absent during the daytime, and many preflexion larvae are present during the night. Glassy sprats are pelagic and live inshore. They are found in shallow seagrasses (Jelbart et al., 2007), over sand adjacent to seagrasses (Connolly et al., 1999), and in the shallow sandy parts of bays and estuaries (Whitehead, 1985). Glassy sprats are distributed across the Coral Sea, the Tasman Sea, and the South Pacific. According to the records, the location where the fish has been found is from Hervey Bay in Queensland through to the mid southern coast of NSW, including, Brisbane River, Mary River Heads, Caloundra, Moreton Bay, and Noosa River in Queensland; Port Stephens, Lake Illawara, Lake Macquarie, Sans Souci (Botany Bay), in Sydney, Harbour and Jervis Bay in NSW. The fish assemblage of glassy sprat in seagrass beds close to the estuary mouth is significantly different from those in beds located far from the mouth of the estuary. The population of glassy sprat in seagrass beds is higher