Today is another guest post from a dear friend of mine who studies the ocean. I got a nice case of food poisoning and she bailed me out with this post, so I am greatly in her debt. Enjoy!

Prepare yourselves – you’re about to have a new favourite fish. Don’t have a favourite fish yet? Well you do now!

Meet … the lumpfish (or lumpsucker, if you’re feeling fancy), Cyclopterus lumpus, the cutest, ugliest fish I’ve ever seen.

An adult lumpfish, hanging out, being lumpy. Image source: Bruce McAdam, Flickr

Fish fascinate me mainly because of the sheer variety of body types. All fish start with the same basic body “ingredients” – head, body, and fins (dorsal, pectoral, pelvic, anal, and caudal) – but these are all modified in fantastic ways leading to the great variety of fish we see today. The lumpfish is no exception.

The lumpfish looks kind of like, well, a lump. Its body is short and stocky; the bottom of the fish is fairly flat, and the top has a large curve, leaving the fish with a bit of a hump-like appearance (as opposed to something like a salmon, which is long and streamlined). There are 7 rows of knobbly, lumpy “spines” arranged along the body, likely the reason behind the name “lump”. The fish has a small mouth at the front of its head topped by 2 tubular nostrils and 2 round beady eyes. Males and females look similar, although the male has a larger head and fins and the female generally reaches a larger size.  One of the longest lumpfish recorded in North America was 23 inches long, although adults generally range from 12-16 inches long and 5 pounds. They vary in colour from grey-green to brown, and the males turn a little red during breeding season.

Lumpfish are a cold-water species and live in the Atlantic Ocean, from New Jersey all the way north to Greenland and east into the Baltic Sea and down south again to Portugal. They are a bottom-dwelling species and spend most of their time clinging to rocks on the sea floor eating small invertebrates and fish, although in some areas they will hide amongst seaweeds and hang out closer to the water surface, especially where the sea floor is muddy, not rocky. This is where another of those fancy body modifications comes in – the pelvic fins of the lumpfish are modified to form a suction cup (hence lumpsucker) that allows them to stick to rocks and the sea bottom, even where waves and strong currents might otherwise wash them away.

A lumpfish preparing to take part in a physiology experiment. You can see the sucker (modified pelvic fins) holding the fish to the bottom of its chamber. Image credit: Tommy Norin

Lumpfish don’t swim much, but will migrate a little during breeding season to find mates and reach good breeding territories. After spawning a sticky, sponge-like mass of eggs, the female heads back to her home rock while the male sticks around, guarding the egg mass and fanning it with his fins to keep water circulating over all of the eggs. Once the eggs hatch, the male leaves and it’s every fish for itself, as the juvenile fish float near the surface for a few weeks until they’re old enough to find something to suck on to.

Lumpfish are more than just adorable though – they’re useful too! Infections can be a big problem in intensive farming, and fish farming is no different. Sea lice, tiny amphipods (related to a pill bug), regularly plague salmon farms, feeding off the salmon, slowing their growth rate, making them susceptible to diseases, and just generally making things unpleasant. In the wild, lumpfish regularly eat small amphipods, and many salmon farming companies in Norway, Canada, and elsewhere are beginning to look to lumpfish as an alternative to chemical pesticides when controlling sea lice on fish farms.

If these techniques work, we just might start to hear more about the cute little lumpfish, something I personally look forward to.