Ibacus peronii, the Balmain bug or butterfly fan lobster, is a species of slipper lobster. It lives in shallow waters around Australia and is the subject of small-scale fishery. It is a flattened, reddish brown animal, up to 23 cm long and 14 cm wide, with flattened antennae and no large claws with meat. The bug has a hard external shell which turns red when cooked.
The species is often confused with the Moreton Bay bug, Thenus orientalis, but they can be distinguished by the placement of the eyes: the eyes of I. peronii are near the small claw (feet), while those of T. orientalis are at the margin of the legs
The Balmain bugs with herb and garlic butter are highlight of Australan seafood dish. The Balmain bug can be made different styles delicious salad and char-grilled lime and garlic Balmain bug, Balmain bug, saffron and fennel risotto and so on tasty dishes. Balmain bug is also a popular ingredient for a perfect barbecue season in Australia.