CHAPTER XXX

FRESH-WATER FISHES

The lowest class of the vertebrate animals consists of the fishes. These are easily distinguished. Some of the reptiles, it is true, are very fish-like. But then they have three chambers in their hearts, while the true fishes only have two. Then fishes never have limbs, the place of which is taken by fins; and further, they breathe water by means of gills. There are other differences as well; but these are quite sufficient to show us that reptiles and fishes cannot possibly be mistaken for one another.

Between the two, however, come several very curious creatures, which seem to be partly reptiles and partly fishes; for they have four slender members which hardly seem to be legs, though they cannot possibly be described as fins, while they possess not only gills but lungs as well.

THE MUD-FISH

One of these is the odd mud-fish of the African rivers. In general appearance this animal looks something like an eel, and it grows to a length of about three feet. Its four long ray-like limbs seem to be quite useless to it, and it swims by means of its tail, along the upper part of which runs a narrow fin. It is a creature of prey, feeding upon other fishes, and when food is plentiful, it just takes one bite out of the lower part of their bodies and no more.

In summer the rivers in which it lives often dry up altogether, and the mud at the bottom is baked as hard as a brick by the rays of the sun. So, as soon as the water begins to get shallow, the animal burrows deep down into the mud, curls itself up like a fried whiting, and falls fast asleep for several months, just as hedgehogs and dormice do during the winter in cold countries. Then, when the rainy season comes and the rivers fill up again, it comes out from its retreat and swims about as before. It is from this habit that it gets its name of mud-fish.

Now we come to the true fishes; and perhaps our best plan will be to read about some of the fresh-water fishes first, and afterward about some of those which live in the sea.

STICKLEBACKS

Let us begin with a little fish which is very common in almost every pond, but is nevertheless very curious and very interesting. When fully grown, the stickleback is about three inches long, and you can tell it at once by the sharp spines on its back, which it can raise and lower at will. It uses these spines in fighting. For the male sticklebacks, at any rate, are most quarrelsome little creatures, and for several weeks during the early part of the summer they are constantly engaged in battle.

At this season of the year they are really beautiful little fishes, for the upper parts of their bodies are bright blue and the lower part rich crimson, while their heads become pale drab, and their eyes bright green! And apparently they are very jealous of one another, for two male sticklebacks in their summer dress never seem able to meet without fighting. Raising their spines, they dash at one another over and over again with the utmost fury, each doing his best to swim underneath the other and cut his body open. When one of them is beaten he evidently feels quite ashamed of himself, for he goes and hides in some dark corner where nobody can see him. And, strange to say, as soon as he loses the battle his beautiful colors begin to fade, and in a very few hours they disappear altogether.

About the beginning of June, all the male sticklebacks which have not been beaten set to work to build nests. These nests are shaped like little tubs with no tops or bottoms, and they are made of tiny scraps of grass and cut reed and dead leaf, neatly woven together. As soon as they are finished the female sticklebacks lay their eggs in them. Then the males get inside, and watch over the eggs until they hatch.

PERCHES

Another very handsome fresh-water fish is the perch, which is plentiful in almost every river and lake in the warmer parts of the whole world. In color it is rich greenish brown above and yellowish white below, with from five to seven upright dark bands on either side of its body, while the upper fins are brown and the lower ones and the tail bright red.

The front fin on the back of the perch, which can be raised or lowered at will, is really a very formidable weapon, for it consists of a row of very sharp spines projecting for some little distance beyond the membrane which joins them together. Even the pike is afraid of these spines, and it is said that although he will seize any other fresh-water fish without a moment's hesitation, he will never venture to attack a perch.

Early in the month of May the mother perch lays her eggs, which she fastens in long bands to the leaves of water-plants. Their number is very great, over 280,000 having been taken from quite a small perch of only about half a pound in weight!

The climbing perch of India, notwithstanding its name, is not a true perch, but belongs to quite a different family. It is famous for its power of leaving the water and traveling for a considerable distance over dry land. It does this in the hot season if the stream in which it is living dries up; and if you were to live in certain parts of India you might perhaps meet quite a number of these fishes shuffling across the road by means of their lower fins, and making their way as fast as possible toward the nearest river!

But how do they manage to remain out of the water for so long?

Well, the fact is that fishes can live for a long time out of the water if their gills are kept moist. In some fishes, such as the herring, this is not possible, because their gills are made in such a way that they become dry almost immediately. But the climbing perch has a kind of cistern in its head, just above the gill-chambers, which contains quite a quantity of water. And while the fish is traveling over land this water passes down, drop by drop, to the gills, and keeps them constantly damp.

When this fish has been kept in an earthenware vessel, without any water at all, it has been known to live for nearly a week!

THE CARP

Another fish which will live for quite a long time out of the water is the carp, which has often been conveyed for long distances packed in wet moss.

This fine fish is a native of the Old World, where it is found both in rivers and lakes, but prefers still waters with a soft muddy bottom, in which it can grovel with its snout in search of food. During the winter, too, it often buries itself completely in the mud, and there hibernates, remaining perfectly torpid until the return of warmer weather. It is not at all an easy fish to catch, for it is so wary that it will refuse to touch any bait in which it thinks that a hook may be concealed. And if the stream in which it is living is dragged with a net, it just burrows down into the mud at the bottom and allows the net to pass over it.

Owing to this crafty and cunning nature, the carp has often been called the fresh-water fox.

The carp is a very handsome fish, being olive brown above, with a tinge of gold, while the lower parts are yellowish white. It sometimes weighs as much as twenty-five pounds, and has been known to lay more than 700,000 eggs! It is domesticated in many parts of North America and other countries.

THE BARBEL

Found in many Old World rivers, the barbel may be known at once by the four long fleshy organs which hang down from the nose and the corners of the mouth. These organs are called barbules, and may possibly be of some help to the fish when it is grubbing in the soft mud in search of the small creatures upon which it feeds. It spends hours in doing this, and a hungry barbel is sometimes so much occupied in its task that a swimmer has dived down to the bottom of the river and caught it with his hands. From this curious way of feeding, and its great greediness, the barbel has sometimes been called the fresh-water pig.

In color this fish is greenish brown above, yellowish green on the sides of the body, and white underneath. When fully grown it weighs from ten to twelve pounds.

THE ROACH

This is one of the prettiest of the European fresh-water fishes, which is found in many lakes and streams. The upper part of the head and back are grayish green, with a kind of blue gloss, which gradually becomes paler on the sides till it passes into the silvery white of the lower surface. The fins and the tail are bright red.

The roach does not grow to a very great size, for it seldom weighs more than two pounds. It lives in large shoals, and in clear water several hundred may often be seen swimming about together.

THE PIKE

One of the largest and quite the fiercest of the British fresh-water fishes is the pike, which is found both in lakes and rivers. In America we have no pike proper, but in some of the great western lakes a very large relative of similar habits known as the maskinonge; and our pickerels are only small pikes. Wonderful tales are told of the ferocity of the pike. He does not seem to know what fear is, and his muscular power is so great, and the rows of teeth with which his jaws are furnished are so sharp and strong, that he is really a most formidable foe. All other fresh-water fishes are afraid of him, while he gobbles up water-birds of all kinds, and water-mice, and frogs, and even worms and insects. And no matter how much food he eats, he never seems to be satisfied.

When the pike is hungry, he generally hides under an overhanging bank, or among weeds, and there waits for his victims to pass by.

The young pike is generally known as the jack, and when only five inches long has been known to catch and devour a gudgeon almost as big as itself. With such a voracious appetite, it is not surprising that the fish grows very fast, and for a long time it increases in weight at the rate of about four pounds in every year. How long it continues to grow nobody quite knows; but pike of thirty-five or forty pounds have often been taken, and there have been records of examples even larger still.

In color the pike is olive brown, marked with green and yellow.

TROUT

Perhaps the greatest favorite of all anglers is the trout, which, in one or more of its various species, is to be caught in almost every swift stream and highland lake throughout the temperate zone, except where the race has been destroyed by too persistent fishing. This happens everywhere near civilization, unless protective laws regulate the times and places where fishing may be done. Similar laws are required to save many other kinds of fishes from quick destruction at the hands of the thoughtless and selfish, and they should be honestly obeyed and supported in spite of their occasionally interfering with amusement.

Trout are graceful in form and richly colored, most of them having arrangements of bright spots and gaily tinted fins. The common trouts of Europe and the eastern half of the United States and Canada are much alike; but in the Rocky and other mountains of the western shore of our continent others quite different are scattered from the Plains to the Pacific. One of the most interesting and beautiful of these, the rainbow-trout, has been brought into the East, and has made itself at home in many lakes and rivers of the Northern States and Canada.

The trout is an extremely active fish, and when it is hooked it tries its very hardest to break away, dashing to and fro, leaping, twisting, and fighting, and often giving the angler a great deal of trouble before he can bring it in. In small streams it seldom grows to any great size, but in some of the Scottish lochs and lakes of Maine trout weighing fifteen or even twenty pounds are often taken. It is sometimes considered, however, that these belong to a different species.

THE SALMON

More famous even than the trout is the salmon, the largest and finest of all our fresh-water fishes, which often reaches a weight of forty-five or fifty pounds, and sometimes grows to still greater size.

It is hardly correct, however, to speak of it as a fresh-water fish, for although salmon are nearly always caught in rivers, they spend a considerable part of their lives in the sea.

Salmon are of two kinds--the Atlantic and the Pacific species; and the life-history of each is a very curious one.

During the winter the parent fishes of the Atlantic salmon, which used to be exceedingly numerous in all our northern rivers emptying into the Atlantic, and still haunt the rivers of Northeastern Canada, and of Scotland, make their way as far up a clear and gravelly river as they possibly can, till they find a suitable place in which to lay their eggs. The mother then scoops a hole at the bottom of the stream, in which she deposits her eggs in batches, carefully covering up each batch as she does so. At this time both parents are in very poor condition, and the males are known to anglers as "kelts." For a time they remain in the river, feeding ravenously. Then in March or April they travel down the river and pass into the sea, where they stay for three or four months, after which they ascend the river again, as before.

Meanwhile the eggs remain buried in the gravel for about four months. At the end of that time the little fishes hatch out, and immediately hide themselves for about a fortnight under a rock or a large stone. You would never know what they were if you were to see them, for they look much more like tadpoles than fishes; and each has a little bag of nourishment underneath its body on which it lives. When this is exhausted they leave their retreat and feed upon small insects, growing very rapidly, until in about a month's time they are four inches long. They are now called parr and have a row of dark stripes upon their sides, and in this condition they remain for at least a year. Their color then changes, the stripes disappearing, and the whole body becoming covered with bright silvery scales.

The little fishes are now known as smolts, and, like their parents; they make their way down the river and pass into the sea. There they remain until the autumn, when they ascend the river again. By this time they have grown considerably, weighing perhaps five or six pounds, and are called grilse. And it is not until they have visited the sea again in the following year that they are termed salmon.

When salmon are ascending a river and come to a waterfall, they climb it by leaping into the air and so springing into the stream above the fall, trying over and over again until they succeed. When the fall is too high to be climbed in this way, the owners of the river often make a kind of water staircase by the side of it, so that the fishes can leap up one stair at a time. This is called a salmon-ladder.

NORTH PACIFIC SALMON

Now this description would not at all fit the case of the salmon which live in the North Pacific and ascend the rivers of California, British Columbia, and Alaska, and of Siberia and Japan on the other side of the ocean. These are the salmon which supply the whole country, and many other countries, with their pink flesh, boiled, and sealed in cans, so that it may be sent long distances and kept many months without spoiling. Every spring and summer, at different times according to the locality and the species--there are five kinds of importance, caught for the trade--vast numbers of them enter the mouths of the rivers and begin to make their way up-stream in their effort to reach the shallow head waters of each river, and of every one of its tributaries. It is at this time that they are caught by spearing, netting, and various contrivances; but laws prevent any general obstruction which would altogether stop the advance of the host, so that while tens of thousands are taken great numbers escape and pass on, as it is necessary they should do in order to lay eggs and so keep up the race.

This takes place far up at the heads of the streams in the foothills of the mountains; and having deposited the spawn, late in summer, the spent fish begin to drift down stream again. But all this time they have been eating nothing, they are worn with the long struggle against the rapids, often wounded by sharp rocks, and are good for nothing to catch or eat. In fact, so fagged out and weak are they that all of them die before any reach the mouth of the river. It is a strange fact that of all the vast host of salmon which each summer climb the rivers not a single one gets back to the sea.

A year later, however, the young hatched from the eggs which were left behind them at the heads of the streams swim down the rivers and enter the ocean. There they remain, probably not very far from land, for two or three years, feeding and growing until they are of full size and strength; and each season a class of them, having reached the right age and condition to spawn, force their way up to the spawning-grounds, to leave their eggs and then die, as did their parents before them.

EELS

The only other fresh-water fishes which we can notice are the eels, which look more like snakes than fishes, for they have long slender bodies, with a pair of tiny fins just behind the head, a long one running along the back and tail, like a crest, and another, equally long, under the body. And they are clothed with a smooth, slimy skin instead of with scales.

These curious creatures live in ponds and even in ditches as well as in rivers, and are very plentiful in all parts of the northern hemisphere. During the daytime, although they will sometimes bask at the surface in the warm sunshine, they generally lie buried in the mud at the bottom of the water, coming out soon after sunset to feed. And when the weather is damp, so that their gills are kept moist as they wriggle through the herbage, they will often leave the water and travel for some little distance overland.

They frequently do this when they are traveling toward the sea. For it is a strange fact that, although they are fresh-water fishes, eels both begin and end their lives in the sea.

In the first place, the eggs are laid in the sea--generally quite close to the mouth of a river. When the little elvers, as the young eels are called, hatch out, they make their way up the river in immense shoals. In the English river Severn, for instance, several tons of elvers are often caught in a single day; and about thirty million elvers go to the ton! After being pressed into cakes and fried, these little creatures are used for food; but they are so rich that one cannot eat very many at once.

When they have traveled far enough up the river, most of the elvers which have escaped capture make their way to different streams and pools and ditches, and there remain until their growth is completed. They then begin to journey back to the sea, and when they reach it they lay eggs in their turn. After this, apparently, they die.

In the rivers of South America a most wonderful eel is found which has the power of killing its victims by means of an electric shock, wherefore it is called the electric eel. The electricity is produced and stored up in two large organs inside the body, but how it is discharged nobody knows. If the fish is touched it merely gives a slight shudder. But the shock is so severe that quite a large fish can be killed by it, while a man's arm would be numbed for a moment right up to the shoulder.

LAMPREYS

The lamprey, which is found plentifully in many northern rivers, is very much like an eel in appearance. But it has no side fins, and instead of possessing jaws, it has a round mouth used for sucking, and resembling that of a leech; and on either side of its neck it has a row of seven round holes, through which water passes to the breathing-organs.

Lampreys seem to spend the greater part of their lives in the sea, but always come up the rivers to spawn. They lay their eggs in a hollow in the bed of the stream, which they make by dragging away stone after stone till the hole is sufficiently deep. Very often a large number of lampreys combine for this purpose, and make quite a big hole, in which they all lay their eggs together.

The length of the lamprey is generally from fifteen to eighteen inches, and its color is olive brown.