No ornament for the drawing-room or parlour can possibly be more beautiful than a well-stocked and tastefully-arranged aquarium; nor is there one likely to be productive of a greater amount of pleasure and amusement. And it is instructive as well as amusing, for by means of it the statements of writers relative to the habits of certain marine animals may be verified by personal observation, and even difficult problems in natural history satisfactorily solved. Aided by one of these 'mimic oceans,' let the reader commence the practical study of marine zoology, and I have little fear of his ever becoming tired of it.

When pursued even in the most humble way, this recreation yields a degree of interest greater than any other 'hobby' can produce, at least in an equal space of time. If engaged in business during the day, the student can always devote an hour morning or evening to the aquarium, and when least expected, some circumstance will take place to excite his wonder, and fill his mind with deep and devout reflection. Moreover, the young naturalist will undoubtedly derive pleasure from his endeavours to establish published facts relative to many of his little prisoners; pleasure in noting down any interesting anecdote that may occur; pleasure in knowing that his time is being profitably spent; and above all, that he is making himself acquainted with objects framed with marvellous skill and care by the hand of the Almighty:—

Without further preface, I shall now proceed to offer some practical hints relative to the establishment of a marine aquarium. And, as some of my readers may be perfectly unacquainted with the subject, I shall treat it in as simple a style as possible. If, however, the experienced zoologist will kindly follow me to the end of the chapter, it may be that he will find some hints sufficiently new and useful to repay him for his trouble.

First, then, in regard to the tank. This indispensable requisite may be procured at certain shops in almost every town in the United Kingdom. Its price varies from two or three shillings to £20. The expensive kinds are generally oblong in form, but their construction being somewhat intricate, they are apt to get out of order, unless made by skilful and thoroughly competent artistes. Under certain circumstances, there is no doubt that an oblong tank of moderate dimensions is a great desideratum; but what I wish particularly to impress upon the mind of the reader is, that a large tank is not at all necessary in order to study the habits of marine animals; indeed, the more capacious the vessel, the more difficult becomes the task of watching the secret movements of any of its occupants. On this account it not unfrequently happens that a common glass tumbler becomes of much greater service to the student than the most elaborate aquarium.

The tanks which I use are circular in form, the largest being not more than sixteen inches in diameter, by seven inches in depth. Its cost was four shillings. Each one rests on a base of mahogany, elevated on turned legs to a height of nine inches.

Some persons object to the circular tank, on the ground that its occupants when seen from the sides appear magnified. This fact, as I have elsewhere remarked, is rather a recommendation with me, as it presents more distinct views of each movement in the vessel, and whenever I wish to see the objects of their natural size, I can do so by looking in from the top.

On the edge of the tank are placed three chips of gutta percha in which are inserted three steel pins with brass heads; on these there is laid a circular piece of common glass, cut two inches larger than the diameter of the tank. As the 'pins' are about three-quarters of an inch above the tank, they allow a current of air to pass over the water, and also prevent, to a certain extent, particles of dust from falling in. On the edge of the movable lid I paste some crimson lace, which serves for ornament, and also prevents the glass from cutting the hand of any person moving it about. Sometimes I have a circular piece, about four inches in diameter, cut out of the centre of the glass lid, which allows the latter to be lifted off easily.

A glass syringe to aerate the water occasionally, a camel-hair pencil, an ivory crotchet pin, and a pair of gutta percha forceps, complete the whole machinery of the aquarium, the cost of which is so trifling that the poorest person might manage to procure them.

One great point in favour of an aquarium, and one by no means generally understood is, that having once filled the tank with salt water, it will last for months, and even years, if proper care be taken, without requiring one particle of sea-water to be again added; for as the water evaporates, the salt falls to the bottom, and the deficiency may be supplied with fresh water from the cistern or filter. In order to ascertain when the sea-water is of the proper density, you require to have a 'gravity bubble,' which can be had for sixpence. This may always be kept in the tank. When 'all's well' it sinks to the bottom, and when anything comes amiss it rises to the surface, but falls again quickly upon the introduction of the fresh water.[20]

A more simple plan is, to mark on the glass the height of the fluid when the tank is first filled, then as the water sinks, raise it again to its original level by means of fresh water.

Many persons decline starting an aquarium on account of the great difficulty of procuring a proper supply of sea-water. This objection, of course, can be offered only by those who happen to reside inland; but even these need not now be discouraged, for an ingenious plan has lately been devised for sending the commodity in question through the post!

Mr. Bolton, chemist, Holborn Bars, London, supplies, not sea-water, but 'marine salts for the instantaneous production of sea-water,' About six ounces is sufficient to make a gallon, by the application of fresh water. The saline material here alluded to, is not an artificial chemical compound, but is produced by the simple process of evaporating sea-water itself. Those individuals so fortunate as to possess a marine villa, or any other more humble residence at or near the sea-coast, have no occasion to resort to the scheme above-mentioned for filling their tanks, a pure supply of sea-water being attainable with scarcely any trouble whatever. A stone jar should be kept for this purpose only, and care taken that the vessel is perfectly free from any smell, as that of spirits, dirty corks, or the like, as any such impurity would quickly spoil the water.

It may not be uninteresting to some of my readers to know, that in France an aquarium cannot be established with the same ease as in England. In the former country 'the whole contents of the sea itself is a contraband article,—that is, the contents of the salt sea of the English Channel or the Atlantic Ocean.' One writer tells us, that staying on the French coast, he kept sea-anemones alive in glasses, but was frequently warned by his friends to be careful how he fetched water from the sea, lest the custom-officers should interrupt him. 'My bottle,' to use the writer's own words, 'being very small, they let it pass, on the principle that the law does not care about extremest trifles; had it been a pailful, the case would have been different. A lady keeping a marine aquarium, explained her wants to the local head of the customs. He came and saw it—found it beautiful, and being a gentlemanly man, with some love for natural history, he gave a written order for the procuring of any reasonable quantity of water from the sea. Every time the needful element was brought from the shore, it was accompanied by its passport, as formally as if it had been a cask of wine, or a suspicious stranger. French salt sellers thus enjoy the height of protection; they are protected even from their colossal competitor, the sea!'

I do not know a prettier sight than that exhibited by a healthy aquarium on a fine summer's day; the effect of the sunshine upon it being to cause innumerable bubbles of oxygen—that look like balls of quicksilver—to form on every weed, shell, and smallest pebble. On looking through the transparent sides of the vessel, small particles hitherto resting on its base, may be seen slowly arising to the surface of the water, each buoyed up by a miniature gas balloon. The broad, ribbon like fronds of the ulva, from the self-same cause, float upwards, and reflect a beauteous emerald hue upon all objects that lie beneath; while the glass bulb, placed in the tank as before stated, to denote the density of the water, at such a time belies its mission, and covered with numerous argent globules, mounts gracefully in companionship with the sea-weed, until shades of evening approach, when its buoyancy gradually subsides, and once more it falls to its original resting-place.

Wherever the above phenomenon is apparent, rest assured that the aquarium is in good condition. It is, in fact, to the oxygen thus given out by the plants and infant vegetation that the animals owe their existence. If no algÆ were introduced, the water would become impure, and unless changed often, your little colony would surely die,—at least those of its members who were unable to rise above the fluid, and occasionally breathe the fresh air.

The secret herein involved, that animal and vegetable respirations counterbalance each other, has only of late years been discovered; yet it is apparent to any observing eye at the sea-shore; there we never meet with a rock-pool containing living animals, that is not more or less adorned with sea-weeds.

The green Lettuce Ulva, so abundant in rock-pools, the sea-grass, which covers almost every fixed object at the sea-shore, or the well-known dulse or Chondrus Crispus, form the only sea-weeds that it is necessary to introduce into an aquarium. In fact, one or two fronds of the Ulva Latissima alone, will answer perfectly well to purify the water of even a comparatively large tank. I have often been surprised to find how small a quantity of algÆ was required for the purpose mentioned. After allowing a single frond to float for a few days in a tank, in which some sea-water was newly deposited, I took it out, and for an entire twelvemonth the water remained healthy and as clear as crystal.

The arrangement of the 'stock' of an aquarium is quite a matter of taste; perhaps no two persons adopt precisely the same plan. It may, therefore, be advisable, as this matter is so arbitrary, for the writer to state how his own tanks are mapped out, leaving it to his readers to imitate the arrangements, or adopt a style of their own as they may think proper.

At one time I used to make a grounding of sand, but this plan is not to be recommended, even though it be one highly approved of by several species of crabs, &c. White pebbles do very well, but I now prefer to cover the base of the tank with crushed shells, washed very clean.

The following is a sketch of one of my tanks as it at present stands:—

In the centre of the vessel is a semi-circular arch, formed of pure white Sicilian marble, which has to my eye a most pleasing appearance. Around it, and indeed over the entire floor of the tank, are strewn chippings of the same material as the centre piece itself.[21] From the arch, at certain intervals, hang various sized specimens of the Mytilus edulis, which have gradually advanced to their more or less elevated positions entirely by their own unaided exertions. Near hand a hardy A. mesembryanthemum has taken up his abode, and sits with ever expanded tentacles, motionless and happy. On either side of the Anemone is deposited a riband of Doris spawn, that undulates to and fro whenever by any chance the water is in the slightest degree disturbed. Several soldier crabs, of course, act as sentinels of the tank, and appear to be ever 'on duty,' marching about in all parts of their subaqueous habitation; while beneath the marble fragments repose, each with his 'weather eye' open, a small Maia squinado, two long-armed crabs, and a small Carcinus mÆnas. On the sides of the vase rest a Limpet, a Trochus, and two fine Periwinkles, with skin of glossy blackness. The shells of either 'Buckie' is covered with myriads of quicksilver globules, that rest on the tips of the young and rising vegetation like dew upon the bladed grass. As I write, upon the inner surface of the water, like a fly upon the ceiling of a room, an Eolis and two pearly white Dorides lie idly floating in close companionship. Beneath them, upon the verge of the aperture of a large empty whelk shell, sits a pretty, cream-coloured Plumose Anemone (A. dianthus). On two blocks of stone repose several specimens of that mysterious animal the Pholas, who, by my unkindness, are thus made to become members of the marine 'houseless poor.' Several young specimens of these bivalves are seated, in a piece of rock, and daily engaged in 'boring.' A stick of wood, formerly the slender twig of a tree, is thickly clustered with fairy-handed acorn barnacles and serpulÆ, and being placed against the glass, the movements of these singularly beautiful creatures can be watched with ease. Then there are two Star-fishes, a pack of three little Blennies, and a Five-bearded Rockling, whose singular movements I have previously alluded to. Against the arch some fronds of ulva are anchored, while at chosen spots specimens of delicate sea-weeds are also fixed—these rising up, and being magnified through the sides of the vase, have a pleasing effect, even to the eye of a child.

It is a pretty sight to watch the fishes glide under and around the marble arch, or throw themselves upon its highest point, there to enjoy the fresh air, and have a pleasant 'crack' together. This expression is literally correct, for the Blennies, when thus situated, usually make a kind of noise not inaptly expressed by snapping the nail of the thumb and finger together.

The foregoing animals which constitute the entire stock of one tank, are, I am proud to state, all in a healthy condition, and if we may judge by appearances, all contented and happy. It will be from no fault of mine if they do not long continue thus, and exhibit no signs of yearning for their native haunts by the sea-shore.

In another tank I have introduced as a centre object a fine piece of white coral, the higher branches of which rise above the surface of the water. The roughness of the coral seems to be much approved of by many of the animals, who are not slow to avail themselves of the facility thus afforded them of climbing and otherwise exercising their peculiar propensities. When purchasing coral, care must be taken to procure a specimen that has not undergone any cleaning process, for although such may be more pleasing to the eye, it is not so suitable for a 'centre piece' as the cream-coloured, and less expensive coral.

A third aquarium which I possess is fitted up in a somewhat novel style, which offers, for certain purposes, some slight advantages over others that I have seen employed. It can be adopted in almost any kind of tank; but the one under consideration is circular in form, and is, in fact, a bell-shaped inverted fern glass, the knob of which is sunk into a stand of wood supported on three legs.

The plan alluded to, which was suggested to the writer by an ingenious friend,[22] consists of the introduction of a floating centre piece composed of gutta percha, which serves as a resting place for various small animals, such as ActiniÆ, Mussels, Barnacles, SerpulÆ, and even Pholades and Cockles. At the base of the vessel, which is quite uncovered, rest sundry members of the crustaceous family, whilst fishes of various kinds swim freely about over the entire vessel free from all annoyance.

The question will doubtless be asked, 'How can I procure the centre piece here spoken of?' I answer, Make it yourself; a little skill combined with patience and gutta percha being all that is required. The following directions will serve to aid the young reader who may wish to test his manipulative powers.

Procure a thin piece of gutta percha, and lay it in hot water for a few minutes until it is thoroughly soft and pliable. Then get a globe—an orange will do if nothing better offers—and cover it with the above material. Having done this, throw it into cold water, and when hard, cut the fruit in two, so as to leave the gutta percha cast to the shape of each half.

Next make a circular tray about eight or nine inches in diameter, and turn up its edge about half an inch all round. Then heat the brim of each cup, and fasten them to the centre of the upper and under part of the 'tray.' The structure will then float in water. This, however, is not all that you want, as your centre piece must always be entirely immersed. First bore a few holes in the tray, then fix a pretty shell, with a hole in it, to the base of the lower 'cup,' and also form a loop of gutta percha, from which to suspend, by means of a piece of silk, a fragment of stone or marble of sufficient bulk to balance the centre piece, and sink it an inch or two below the surface of the water. At the centre of the upper cup fasten a small piece of gutta percha tube, at the end of which the valve of a Pecten may be attached as an ornament. The whole structure must be gently warmed and entirely coated with fine sand; then tastefully decorated with shells and fronds of green Ulva, and the crimson Delesseria Sanguinea.

Sometimes I introduce a globe of glass as a buoy, and to its centre attach the tray of gutta percha.

A useful centre piece, a specimen of which I have had in use for several months, may be formed thus. Make a tripod of gutta percha, on the top of which attach the valve of a Pecten. From the centre of this object fix a branch of coral by aid of gutta percha, in such a way that it rises above the water in the tank. From under the shell pieces of coral may be made to branch out in various directions. The stand should be coated either with crushed shells or sand, to give it an ornamental appearance.

It is often a source of annoyance to find the base of the aquarium so thickly covered with dirt, &c. To get rid of this great 'eye sore,' without emptying and re-arranging the tank, I call in the aid of a very simple and effective instrument. By its application all objectionable matter may be gradually removed without in the slightest degree disturbing the water, or materially displacing the objects situated at the base of the vessel.

The instrument mentioned is composed of a gutta percha globe, made in the manner previously described, into one end of which is inserted a tube of gutta percha or glass about four inches long, and at the opposite end of the ball is introduced a second tube about eight inches in length.

To use this instrument, close the orifice of the longest tube, and plunge it into the water over any spot where the debris is collected, then by removing your finger from the end of the tube, the impurity will be instantly sucked up into the ball. By again placing the finger in its former position, the siphon may be lifted out of the tank, and its contents allowed to run off into a jug or basin placed near for the purpose.

This operation must be repeated until the whole of the offending particles are removed. Of course, more water will be drawn off than is necessary, but it can easily be poured back into the tank as soon as the sediment has been fully precipitated.

Aquaria are generally much more difficult to keep in order in summer than in winter, owing to the rapid and profuse growth of minute vegetation which renders the water opaque and exceedingly unpleasant to the eye.

This ugly opacity I at one time attributed to decaying animal matter, for I could scarcely believe that the mere increase of the algÆ spores could produce such a vile effect. Experience, however, has proved that the latter was in reality the true cause. I tried often by syringing the water, or drawing it off by means of the siphon, or stirring it about in all manner of ways, to remove the objectionable muddiness, but always without success. Limpets and Periwinkles seemed quite useless. Nor did shutting out the rays of light for a few days have any perceptible effect in subduing the growth of the algÆ which collected with wondrous rapidity, and arrayed each stone, shell, pebble, and even the poor crabs, in a greenish garb.

I was therefore under the necessity, on several occasions, of renewing the water, and considering that my residence was several miles from the sea-coast, this task was by no means a pleasant one. What made matters still more provoking, was the fact that the rejected fluid seemed perfectly free from all offensive smell. I now adopt the following novel method for removing the opacity of the water, without the latter being changed, and also for preventing the too abundant growth of the algÆ at all seasons.

The plan in question (which requires, as already shown, to be carried out with extreme caution by the inexperienced aquarianist) is merely to dilute a small quantity of alum in a wine-glass full of water, and then mix it with the water contained in the aquarium. A pellet of alum about the size of a pea is sufficient for the purpose, if the tank be of moderate size. And if inserted on the first appearance of dimness in the water, much future trouble will be saved.

Supposing the water to have become opaque, proceed thus—Draw off a portion into a large jug, and mix with it the diluted acid as before stated, then let the jug remain undisturbed for about twelve hours. The vegetation having been deposited in flakes at the base of the vessel, the water should then be gently strained off through a piece of fine muslin into a second receptacle, which, in its turn, should be allowed to stand for some time, and the contents again strained as before. This process it is advisable to repeat several times, until the whole of the fluid in the tank has been thoroughly cleansed from impurity.

Should the water be returned too early, an unpleasant fur coating will appear over the entire base of the tank. This can be easily removed by means of the siphon. Let one end of this instrument, when in action, be passed gradually over the lower portion of the vase, and in the course of a few minutes every sign of 'fur' will be obliterated with the loss of but a small portion of water. When once the fluid has been clarified in the manner here mentioned, there is little fear of the young aquarianist being again troubled in like manner for many months, the acid apparently preventing the algÆ from being reproduced to any such excess as hitherto.

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