Western Blue-spot Goby

Pseudogobius olorum

The Swan River goby (Pseudogobius olorum), also known as the bluespot goby, is a small fish in the family Oxudercidae. Adults reach only about 5 cm with a slender body showing mottled pale brown to yellowish-brown coloration with darker blotches. Males display a diagnostic blue spot on the rear of the first dorsal fin and a blue margin on the anal fin. This species inhabits estuaries, river mouths, and coastal lagoons at depths of 0-3 meters around most of Australia except the northwest. They are commonly found in muddy areas and seagrass beds in the upper reaches of estuaries, and can penetrate upstream into freshwater. Swan River gobies are carnivorous, feeding on small invertebrates. Males guard and fan eggs deposited on the underside of shells and debris. Originally described from the Swan River in Perth, Western Australia, they are one of the most common small fish in Australian estuaries.