When I first saw the name of this fish the thing that popped into my head was the ‘plum pudding model’ of the atom, first proposed by J.J. Thomson in 1904. Before the nucleus of the atom was discovered, a whole slew of models were proposed; Thomson suggested that the atom was a positively charged ‘pudding’, and electrons were negatively charged ‘raisins’ dotted throughout the atom. Apparently this term isn’t reserved for Thomson’s atomic model: the plum pudding cod is a fish covered with little ‘raisins’.

Alternative names for the plum pudding cod are similarly descriptive: it is also called the polka dot cod, panther grouper or humpback grouper. I will continue to refer to the fish as the plum pudding cod, because I think that name is the most amusing.

See how spotty they are? Image by Udo Schröter, CC BY-SA 3.0, via Wikimedia Commons.

Plum pudding cod are found in waters around Australia, in southern Japan, and in the east Indian Ocean. They live in reefy areas, often preferring to spend their time in dead reefs where there’s lots of nice, soft sand. Plum pudding cod usually don’t stray past depths of 40 m.

The most distinctive feature of plum pudding cod are, of course, their spots. They grow to be reasonably large, reaching 70 cm in length. The background colour of a plum pudding cod (so the ‘pudding’ part) is usually reddish brown or yellowish brown.

Plum pudding cod are sequentially hermaphroditic, meaning they start as one sex and then change into the opposite. In the case of plum pudding cod, they start as female and then turn into males as they age. These cod aren’t great parents — they scatter their eggs in open water while another cod fertilizes them, and then simply swim away, leaving their kids on their own.

Young plum pudding cod look a bit different from the adults. Their spots are larger but less numerous, and they tend to swim with their heads pointing at the ground. This may seem strange, but adult pudding cod also swim oddly, moving slowly and then turning suddenly. Apparently it sometimes looks as if the fish are trying to swim upside-down.

I don’t think I’ve ever actually had a plum pudding, but at least it’s lent its name to some interesting things. Also a fish named after plum pudding makes me think of a filet studded with raisins, which sounds kind of gross but could be tasty if done correctly. Who knows.

Cover image by Arpingstone, Public domain, via Wikimedia Commons, cropped to fit