The Eastern Blue Devil Fish (Paraplesiops bleekeri) is also known as the Bleakers Blue Devil Fish. It is a shy, secretive fish that is found inside caves and under ledges in inshore reefs in NSW estuaries and offshore waters from three to thirty metres. It occurs on the east coast from southern Queensland to Montague Island, but is most common in NSW from Sydney southwards to Ulladulla. Around Sydney it occurs in the more saline parts of estuaries, along the rocky coastline and around offshore islands.
They are fecund breeders, however juveniles are rarely seen. They are often solitary and are most active during the night however little is known about their diet. The Eastern blue devil fish is listed as a protected fish in NSW, and there are heavy penalties for taking, selling or possessing them.
The Eastern blue devil fish is most easily recognised by its banded pattern of blue and white strips on the body, blue spotted head, blue dorsal and anal fins and yellow caudal (tail) fin and base and pectoral fins. The pelvic fins and posterior dorsal and anal fins are elongated. When the blue devil fish spreads these fins they overlap, making the fish appear larger.
It is thought that the male defends a territory in a cave or overhang in order to attract a mate and will drive other males away. They mate in spring. The breeding season for the Eastern blue devil is between the months of October and March. The species lays its eggs in a group or nest that is glued to the roof of a cave until they hatch. Free swimming larvae, approximately 4mm long, hatch from the eggs and settle around reef areas when they have grown to about 10mm. It grows to 40cm in length.