The Grey Triggerfish (Balistes capriscus)

I like fish, I'm interested in them both underwater and on my plate. I have a reasonable knowledge based mainly on experience, shored up with solid facts from the wikipedia and fishbase.org. I'm always eager to learn about the sea and its inhabitants.

As with the birds I have the local fish identified, the ten common or garden species and the rarer ones. The ones that I know I might see but hardly ever encounter. And others, that although they turn up on the fishmonger's slab having journeyed from afar, are almost things of legend, like the dusky grouper (Epinephelus marginatus).

A new sea floor over which to snorkel brings the pleasure of anticipation. I have discovered just how painful is the poison of the weever fish (Trachinus draco) and how enduring the discomfort of the Pelagia noctiluca jelly fish sting. I've watched bluefish (Pomatomus saltatrix) hunting anchovies and have even been checked out by a pair that followed me for many metres, sniffing at my toes. I have caught octopus (Octopus vulgaris) and felt the pinch of their parrot-like beaks.

Recently, in Formentera, floating 10 metres or so above a barren bottom I saw an old rudder lying on the sand. A wrasse was hovering around one edge, often a sign that an octopus is in residence as the diminutive wrasse makes meals of pedators' scraps. I emptied and filled my lungs a few times then dived down, holding my nose and blowing every 2 or 3 metres to compensate the mounting pressure. I looked underneath the rudder, no octopus but another predator; a triggerfish, about 40cm long, bold and ugly.

I didn't hang about. I knew the triggerfish to be aggressive and I was running out of oxygen anyway. At the surface I hung in the water breathing. Suddenly I felt something grab my foot, I turned with a great flurry of limbs and saw the triggerfish clamped upon the knuckle of metatarsal behind my left little toe. And it didn't want to let go. I shook my foot hard and shoveled water at it, the fish backed off a bit. Then it came at me again. I kicked and pushed bubbles, my only defense. It had a particularly calculating stare and it looked at me coldly as it followed my messy backpedalling towards the boat from which I'd dived. After a while it desisted and I examined the two small holes on the top of my foot that were leaking blood into the water. It wasn't a serious wound. I climbed aboard wondering just why the fish had given me such an evil reception.

On the internet I confirmed that the triggerfish is indeed a cantankerous blighter, with a powerful jaw and sharp teeth but, more interestingly that it becomes defensive when protecting eggs. Even more interesting was the discovery that the fish's territory has the shape of an inverted cone, the apex at the bottom and the broadest part at the surface. So, if you encounter a triggerfish on the bottom and he doesn't look happy you should swim away horizontally. My mistake was to ascend and as I rose I further trespassed on his patch. On the surface above the nest I was bang in the centre of the fish's territory and as such a threat that needed to be dealt with.

I applaud the trigger's cojones and treasure my new fishy knowledge—I won't forget that icy stare—as well as the pin prick scars on my foot.