This bowl is from the 1950s, made by the large ceramic producer, Diana Pottery Sydney.
Diana had a huge inventory of pieces during their production and their styles ranged from the everyday work piece to extravagant hand painted items.
This bowl is so 50s - the pale green glaze with the hand painted prawns (or shrimp if you prefer). Model number S120 moulded to the base, and Diana stamped also.
Width 20cm (8in)
I have previously posted some polka dot pieces by Diana with a bit more history:
http://www.collectorsweekly.com/stories/125541-diana-pottery-australia-1950s