THE BULL-HEAD, OR MILLER’S THUMB,
(Cottus gobio,)
Is found in clear brooks and rivers in most parts of Europe. It is from four to five inches long; the head is large in proportion to the body, broad and depressed; the gill fins round, and beautifully notched. The mouth is large and full of small teeth; the general colour of the body is a dark brownish black. This fish is remarkably stupid, and may be caught with ease by the most inexperienced angler, even with a bent pin and coarse thread. Its hiding-places are among loose stones, under which the peculiar flattened form of its head enables it to thrust itself. Its popular name seems to have suggested itself from the resemblance the head of the fish is supposed to bear to the form of a miller’s thumb, the peculiar conformation of which is produced by his mode of testing samples of meal.
THE STICKLEBACK, (Gastuostius aculiatus,)
Is one of our smallest fishes, and appears to live indifferently in fresh and salt water. It is exceedingly common in every pond, and may be caught easily, either with a hand-net, or by fishing for it with a small worm tied to the end of a piece of cotton; he bites at this so boldly that he may be drawn out of the water without the aid of a hook. His name of Stickleback is given to him from his having thin spines on the back instead of a fin; the sides of his body are covered with thin bony plates, and his ventral fins consist of single, strong, and sharp spines, which constitute formidable offensive weapons.
The Stickleback, although so common, is one of the most interesting of fishes, on account of the singularity of its habits in the breeding season. Instead of depositing its eggs in the sand or mud, and leaving them to take care of themselves, the Stickleback builds a curious nest of fragments of vegetable matter, and defends this most valiantly against all intruders until the hatching of the young; the parental solicitude does not cease until the young Sticklebacks have grown too big to be any longer controlled. One curious feature in the business is, that it is the male that takes all this trouble; he builds the nest, exposes himself to every danger in its defence, and watches anxiously over the vagaries of his young progeny, the female having nothing to do but to deposit her eggs in the already prepared nest.
The Stickleback is an extremely pugnacious fish. The males fight together furiously, and the colours of their bodies become much more brilliant while they are so occupied than at any other time.