Nature Diary

Fish of the Rocky Shore

Beneath the waters of La Gomera there are not only large stretches of sand, but also a plentiful supply of rocky areas. For me, this makes the place very interesting, because I can watch both habitats at the same time and see the very different fish which live in each of them.

The bigger fish living on the sandy bottoms rely on hunting smaller fish, and since there is no plant life there the smaller fish are scavengers. All of the fish – both the hunters and the hunted – are disguised to be precisely the same pattern and colour as the sand, betraying their whereabouts only by shadows and by the scars which a few of them carry. They hunt not by chasing but by creeping up and springing out.

The fish of the rocky shore live very different lives. Many, like the damsel fish, the ornate wrasse, and the parrot fish are very brightly coloured. They do not hide; they stay out in the open. They do not skulk along on the bottom; they are mid-water fish.

Most mid-water fish live in shoals, hoping, when danger arrives, to hide themselves in the middle of the pack. Those who eat other fish do it by chasing them, not by stealth. Others eat the algae which grows on the rocks – and that, of course, is why the whole lot of them are hanging out in this place. The algae is at the bottom of the food chain. The hunters are at the top. In between them come the crustaceans and the sea slugs, and other such things, and the fish who graze on the weed and the ones who eat the crustaceans.

Some fish eat both algae and small animals, and some actually eat algae and go hunting. One of these is the parrot fish. These swim quite slowly around the sunken boulders, grazing on them with their strong teeth. With their thick, strong scales and their strong sharp beaks they must be fairly safe from other fish.

At first glance the parrot fish seem to be of several different species, but actually they are all the same type.
The huge grey parrot fish are the males. The females are smaller and they are brightly coloured. I believe that the females eat both algae and other fish, because I have certainly seen them grazing on the weed and I have also seen them chasing other, smaller fish. The immature parrot fish don’t seem to do this. I have only seen them eating the weed. They are small, of course, and they are a pale grey brown. It is illegal to catch them because they haven’t had the chance to breed – but in any case, this particular species of parrot fish is very difficult to catch. I have often tried to tempt one of the big grey ones, but I have never managed it, and I have since been told that they never take a hook.

The fish that the parrot fish chase and seem to prey on are very different. Their usual victims are the ornate wrasse and the damsel fish.
The ornate wrasse is another hunter, I believe. It is wonderfully brightly coloured, the male consisting mostly of green with lots of tiny red stripes in it. The body colour fades into a head with a maze of purple, pale blue, and orange. Even the female is very pretty. She is covered in lines of two shades of green and several shades of brown. They are bold little fish and so lovely to look at that I could never want to catch one – but my French friends do, and so do the Spanish fishermen.

I have seen ornate wrasse all throughout the Canary Islands, and in the Mediterranean too, and wherever I see them I also see damselfish there too. These fish also seem to be hunters, but one would never guess it to look at them. They are so pretty, with their dark blue body and their bright blue fins. But I once saw one chasing a smaller fish of its own type up and down the reef.
There is also the fula blanca, which is another damsel, more or less the same, but a lovely shade of purple with yellow fins.

The two branded sea bream and the salema (salpa) are both common reef fish which we also used to see in the Mediterranean. They are both silvery fish, and they can grow to be quite big. They almost always hang around in big shoals, and when the sea is shallow, and the waves are washing past overhead, the whole shoal sways to and fro. When they turn, they all turn in exactly the same moment like a flock of birds. A group of people could not do that. I wonder how the fish and the birds all know, in the same instant, that they are supposed to turn?

The bream are carniverous. They eat small invertebrates, such as shrimps. But the salpa are definitely vegetarians. However, they never waste the opportunity to eat a piece of dead fish. Although they are most common swimming close to the rocks I also find shoals of small salpa living an easy life inside the port, where there is lots of waste after the fishermen have cleaned their fish.

As well as all the common fish which one might expect to see amongst the rocks, there are also some surprises. One of these is the trumpet fish. They are such a strange shape that the first time I saw one I wasn’t even sure that it was a fish! They are long and thin, a bit like a very elongated seahorse, and they hang in the water. They have a long, horsey nose and instead of teeth they have a hole in the tip of their snout.
These fish are quite striking. I have seen them coloured anything from bright orange to muddy brown, and the tail is usually black with big white spots.

With their jawless mouth and lack of teeth I would have thought that they must be filter feeders, eating plankton and detritus, but my book of Canary Islands Sealife tells a different story:
“They eat small fish, which they catch by launching themselves rapidly towards and catching by suction.” (Translated from the Spanish.)
Presumably they suck in with their long snouts and clamp themselves against the fish and keep sucking. I should like to watch one doing this.

Another fish which I sometimes see on the reef is the cuttlefish. I don’t believe that these creatures live here all the while, I think that they are just visiting. They are, of course, not fish at all. They are close cousins of the octopus and are supposed to be very much more intelligent than fish. They have huge eyes, which look at me, and they can change their colour very suddenly, like a light flashing. They swim by flapping the frilly edge of their body. I have never seen them do anything especially clever, apart form the colour changing.

The red-lipped blenny is another common fish amongst the rocks. He spends his whole life lying flat on the rock, eating algae and trying not to be seen. With their funny markinhs I think that they look rather like clowns, watching the world go by and laughing at it – but I suppose this is just my imagination. I wonder what they are really thinking. Perhaps they don’t think at all.
I wonder what it feels like to be a fish… I dont know if I would like living in the sea, because there is always something creeping up behind you. I think I would rather be a reef fish than a fish hiding fearfully on the sandy bottom – but, then again, there might be a moray eel waiting to spring out and gobble me down!

3 Comments

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