Occasionally, on very sunny days in spring or early summer, before the leaves were fully grown, a newspaper would be placed between the glass and the window-pane, or over a corner of the top, to give the desired protection; but the tiny cavern usually supplied sufficient shade, and it was ever a source of unabating amusement to watch the little fellows swim in and out through the arches, darting now here and again there, hiding in the shadow of some moss-grown stone, to spring out a moment later upon an unsuspecting companion swimming leisurely by; their little games of hide-and-seek and of tag were very entertaining to witness, and we children would frequently find ourselves quite excited over the success or failure of our special favorite in the game.
As the aquarium of which I speak was a large one, it frequently had several inmates at the same time; among these the little nippers, or, as the dwellers along the coast of New York State call them, killie-fish—so named by the Dutch settlers from their frequenting the little kills, or inlets, along the shore—always held a conspicuous place. Indeed, these little fishes seem to be blessed with a long string of names entirely disproportionate to the size of their tiny little bodies. In some places they are known as minnows, while on the shores of the Narragansett they retain their old Indian name of Mummychog. They are a bright, lively little fish, darting through the water with such rapidity, that you hold your breath in fear lest they dash themselves against the glass at the end, but they never do; just as contact with it seems a matter of certainty, they suddenly turn a sharp angle, face about, and perhaps come to the front and peer at you through the glass, with their funny little faces pressed up close to its surface. They are of a greenish-gray color upon the back, which gradually shades to a bright silvery tone at the sides, and their eyes, which are large and staring, have a very mild, good-natured expression.
Very different from these are the sticklebacks (Gasterosteus), also fine subjects for the aquarium, for a more pugnacious or plucky little fellows it would be hard to find than these graceful little tyrants, which in early spring are found in our creeks and salt-water ditches in great abundance. As this is the only season of the year in which they can be captured, it is best to be on the watch for them during the last of March or the first of April. A dip-net, made of a piece of mosquito netting caught over a small hoop, and attached to a long, slender handle, is best for catching all kinds of fish for the aquarium, and the shores of bays or salt-water streams supply a greater abundance than the open sea, or the shore washed by the heavy ocean waves. If your globe is the vessel you are to use, the sticklebacks will afford you quite as much amusement as any fish you could find, for aside from their quick, lively manner, they are a very handsome fish. The male is of a rich ruddy color, his little silvery sides giving forth gleams of red or blue, which vary considerably, according to his temper. If he feels quiet and peaceful, they are pale and soft in tone, but if indignant, they become very brilliant, and the little chap with his savage, fiery eye, becomes an object of great respect and terror to all the other denizens of the water within reach of his teeth or sharp little spines. The female is less brilliantly colored than the male, is blunter in build, and has a comparatively mild disposition, leaving all little differences with other fish for her liege lord and master to settle, for which duty he is perfectly well fitted and takes great delight in performing; indeed, so quarrelsome were these little fellows, that they would soon kill all fish of other species in the tank, and when no other subject was at hand, would fall to and fight one another, biting as ugly dogs might do, and spearing with their tiny spines, till one had acquired complete supremacy over all the rest. It is very interesting to watch the process of their nest-building, and to see them, like so many lilliputian carpenters, lay the sticks and hairs in place, working as if their whole life depended upon their unceasing exertions. We used to put in bits of broom-corn split in threads, and bristles from the floor-brush, for materials; and the work of building would generally occupy three or four days. The nest was built in one corner of the box (we were obliged to keep the sticklebacks in a separate glass case, as they killed all the other fish if together) and well up on the sides, with a tiny round hole at the top for the fish to go in and out. After a short time—I do not remember now just how long—hundreds of little fish came out from the nest, and were very lively for two or three days, but in a week they were all dead, and the parents had the waters to themselves once more. We never succeeded in raising the young fish, I remember, but I do not now recall whether any reason was ever ascribed to our failure, or if it was even known.
But to go back to our large aquarium. Fortunately for us, not many fish are as quarrelsome as the sticklebacks, and most of those I shall now describe live together in perfect harmony. The young of larger fish do very nicely for a time in the aquarium, and a young eel is a rather amusing although somewhat sluggish fellow to keep.
The most amusing denizens are creatures of the crab family. The little hermit-crabs, found in quantities on any shelving beach of the bay or sea inlet, create much sport for the young naturalist. These little crabs, you must know, are soft little fellows, for whom nature in a frugal moment prepared no house or covering to protect them from the thumps they might receive from both water and stones; but the little fellows, with a shrewdness one would hardly suspect in creatures so small, rise equal to the occasion, and help themselves to the empty snail-shells left by their more fortunate neighbors. When small they occupy the little black snail-shells, moving from a smaller to a larger as they increase in size. After outgrowing these plainer homes they take possession of the pretty grayish-white shells also found in abundance on our shores. It is frequently quite amusing to watch two fight over a particularly desirable one, which either has chosen for its own, and ofttimes the battle will be long and heavy before either will give up that which he considers by rights his own. If you have one or more of these little wanderers in your globe, remember to put in two or three empty snail-shells for them to flee to when they have outgrown their present abode. Their manner of eating affords a very entertaining spectacle. Clams, either soft or hard, cut into tiny bits, form the principal food for all the dwellers in the aquarium, and a long stick with a needle driven in one end, to form a tiny spear, is used in passing it to them. When a particular crab is to be fed, a bit of clam is taken up on the needle, and lowered down in the water to a position directly in front of him. At first, before he has become acquainted with this mode of dining, he draws in his claws, and nothing but the shell is to be seen upon the bottom; but in a few moments the little fellow lets himself out again, little by little, with a quick, jerky movement, till at last his two little eyes stand in an upright position, and he is ready to seize the tempting morsel. This he does with his longest claw, and holding the clam firm in his grasp, he proceeds to pick it in pieces with the other long claw, and pass it along to the smaller set, which in turn give it to the next in order, until it finally disappears in the mouth itself, and is swallowed by the little creature.
It is important to have two or three snails in your globe to act as scavengers, and keep the water free from the refuse which would otherwise remain on the bottom. These little creatures are often seen moving slowly along on the surface of the glass, feeding upon the green moss or confervæ which accumulates so quickly on all the objects under water. The pipe-fish, a peculiarly shaped specimen, comparatively rare on our Atlantic coast, is worthy a place in your collection; and the shrimp, the acrobat of the aquarium, whose funny little backward movements, when the poor little fellow is frightened, create so much laughter among the little folks, must not be forgotten. Young scallops are very pretty, and when left undisturbed open their shells a trifle, disclosing a beautiful fringe of tiny blue tentacles which wave to and fro with every motion of the water.
The medusæ, also called jelly-fish, with their umbrella-like cover, and long, slender tentacles streaming downward, are pretty for a time, but do not live long after they are taken from the sea. The Cydippe and the Beroe are very lovely specimens of this class, the former particularly is noticeable for its beautiful iridescent colors. The beautiful orange colored medusa is an unsafe inmate, as he very soon kills all the fishes within his reach.
If it is possible, obtain one or more of the beautiful sea-anemones, and add it to your globe; the large, bright-colored members of this class are only to be found in the tropics, but very pretty, delicate specimens are sometimes found in our northern waters, where a rock or bit of stonework is constantly washed over by a swift current. If possible, it is better to take the stone on which they rest, as it is almost impossible to remove them from its surface without killing them. This was, however, done several times with success, and the anemones lived in our aquarium as long as they could be expected to exist in perfectly quiet water. When these creatures are at rest or frightened they draw down into little shapeless masses; but when looking for food they stretch up again, and expand on the top of the long stalk, as we may call it, a beautiful flower-like head, resembling an aster in form, and of a deep brownish-yellow color. When food is passed down to this animated blossom, it will fold its little tentacles one by one around it, and pass it down into its mouth, open to receive it, but which is entirely hidden by the beautiful petals of this delicate flower.
All of you have probably noticed the serpulæ, or worm-like excrescences often seen upon oyster and other hard shells. If one of these shells be taken from the water and immediately placed on the bottom of your aquarium, after a few days, when the little animals feel quite at home, they send out of one end of their slender tubes bunches of the loveliest, delicate brown fern-like feelers, which sway about in the water like the beautiful roadside ferns in a gentle summer breeze.