Channa marulius: the bullseye snakehead
As a grad student down at the UF Tropical Aquaculture Lab, I see a lot of fish. Some are small, some large, some are aggressive, and some aren’t, but one species that never fails to entertain and engage is the bullseye snakehead Channa marulius. There are several introduced populations of this species living in the state of Florida at the moment. They are believed to have been imported from Asia for the live fish markets, and subsequently released into the environment – though whether this was intentional or accidental isn’t known.
While the snakeheads’ roles in campy, melodramatic B-movies doesn’t seem like it should inform their broader perception as a real-world threat, the fact is that their portrayal by the mainstream media hasn’t really been much more balanced. Typing “snakehead voracious predator” into Google, for example, yields a total of over 80,000 hits. In my experience, voracious is definitely pushing it. 
The snakeheads we have at the lab right now were captured in a series of man-made canals down in Boca Raton last fall. Myself, my adviser and my labmate trekked down to Boca with our shock boat and live haul box, ready to electrocute as many of these fearsome creatures as we could, and I wasn’t entirely sure what to expect. For anyone who hasn’t electrofished before, when it’s done from a boat it consists of one person driving and running an electric current through the water that will – in theory - briefly stun any fish in the immediate vicinity, making them easy to net. Everyone else on the boat stands around watching the water for fish and then snags them with a net. Some types of fish are easier to shock than others, but snakeheads as it turns out, are a piece of cake. They are big and obvious making them easy to spot, and when you zap them, they just roll right over and float upside-down like a dead thing. This makes it the simplest of tasks to scoop them right up and fling them into a waiting receptacle on board the boat. Another thing that I was curious about while on this trip was what the locals thought of the snakeheads.
Fairly recently, an episode of the TV show River Monsters was devoted to snakeheads, and part of it was filmed in that same area. It was immediately apparent that the human denizens of the canals are definitely still feeling the effects of that one. There was one woman who told us she was afraid to put any part of her body into the canal now, because it might be chomped off by a snakehead. We tried to convince her that such a thing was highly unlikely, but she seemed unwilling to take our word for it, which I suppose is understandable. 
As it turns out, when left to their own devices, the snakeheads of the Boca canals were not eating puppies or small children, or even other fish for the most part. They were eating dragonflies. Nearly all the items we found in the stomachs of snakeheads we caught on that trip were partially digested, adult dragonflies – and some mysterious white goo the consistency of silly putty that no one has been able to identify. 
Perhaps unsurprisingly, while we were out on the water, there was an amazing number of mating dragonflies flitting about and sitting on the aquatic plants at the surface of the water. Little did they know what lurked beneath. The terror of the deeps (well, actually they tended to stick to the shallows, but “the terror or the shallows” lacks something as far as dramatic effect goes). I felt kind of bad for the little guys. There they were, having a romantic moment, trying to pass their genes on to the next generation of odonates, when suddenly… CHOMP!! They are now officially eliminated from the dragonfly gene pool. Ah well c’est la vie, I suppose. The snakeheads themselves definitely seem pretty invested in their own lives and freedom. One jumped out of the boat and back into the canal. This was after being electrocuted and tossed into a box full of water. A box with a lid, I might add. And that snakehead wasn’t the only one to try and make a break for it.
We had just driven back up to the lab in Ruskin, bearing about over twenty live snakeheads, and ten times as many snakehead carcasses, when we had a second escape attempt. One snakehead, probably close to three feet long, turned out to be smarter than the haul box. As we were preparing his new home at the lab, he managed to knock the aerator that was oxygenating the water in the box out of its slot, jump through said slot, and onto the truck bed, at which point the aerator fell back into place.
This confused us to no end when we got back to the truck, finding an intact box with the lid still clamped in place, and one live snakehead thrashing around next to it. This was troubling, to say the least. Was Swarm of the Snakeheads right? Can they hide in our vehicles and sneak into our homes, laughing maniacally as they try to kill us all? More importantly, were our extensive biosecurity measures going to be enough to contain this ferocious beast? Well, as it turned out, yes.
What we found was that they are finicky little things, and seem to be easily freaked out by fish that are too big for them to swallow whole. One of them had a hard time trying to swallow a tilapia that was a little too large to fit down his throat, and has refused to go near a tilapia since. Even little tiny ones. Punks. They themselves are great fun to eat, however. The lab Christmas fish fry featured a pile of snakehead fillets that were consumed with great enthusiasm by one and all.
