The Atlantic Monthly, Volume 08, No. 47, September, 1861

Hortensius, who possessed three splendid country-seats, constructed in the grounds of his villa at Bauli a fish-tank so massive that it has endured to the present day, and so vast as to gain for it even then the name of Piscina Mircihilis. It is a subterraneous edifice, vaulted, and divided by four rows of arcades and numerous columns,—some ten feet deep, and of very great extent. Here the largest fishes could be fattened at will; and even the mighty sturgeon, prince of good-cheer, might find ample accommodations.

Lucullus, that most ostentatious of patricians, and autocrat of bons-vivants, had a mountain cut through in the neighborhood of Naples, so as to open a canal, and bring up the sea and its fishes to the centre of the gardens of his sumptuous villa. So Cicero well names him one of the Tritons of fish-pools. His country-seat of Pausilypum resembled a village rather than a villa, and, if of less extent, was more magnificent in luxury than the gigantic villa of Hadrian, near Tivoli. Great masses of stone-work are still visible, glimmering under the blue water, where the marble walls repelled the waves, and ran out in long arcades and corridors far into the sea. Inlets and creeks, which wear even now an artificial air, mark the site of piscinae and refreshing lakes. Here were courts, baths, porticoes, and terraces, in the villa urbana, or residence of the lord,—the villa rustica for the steward and slaves,—the gallinarium for hens,—the apiarium for bees,—the suile for swine,—the villa fructuaria, including the buildings for storing corn, wine, oil, and fruits,—the horius, or garden,—and the park, containing the fish-pond and the vivarium. Statues, groves, and fountains, pleasure-boats, baths, jesters, and even a small theatre, served to vary the amusements of the lovely grounds and of the tempting sea.

But it was not to be supposed that men satiated with the brutal shows of the amphitheatre, even if enervated by their frequentation of the Suburra, could, on leaving the city, be always content with simple pleasures, rural occupations, or pleasure-sails. Habit demanded something more exciting; and the ready tragedy of a fish-pond filled with ravenous eels fed upon human flesh furnished the needed excitement. For men blasé with the spectacles of lions and tigers lacerating the bestiarii. It was much more exciting to witness a swarm of sea-eels tearing to pieces an awkward or rebellious slave. Vedius Pollio, a Roman knight of the highest distinction, could find nothing better to do for his dear Muraenae than to throw them slaves alive; and he never failed to have sea-eels served to him after their odious repast, says Tertullian. It is true, these wretched creatures generally deserved this terrible punishment; for instance, Seneca speaks of one who had the awkwardness to break a crystal vase while waiting at supper on the irascible Pollio.

Pisciculture was carried so far that fish-ponds were constructed on the roofs of houses. More practical persons conducted a stream of river-water through their dining-rooms, so that the fish swam under the table, and it "was only necessary to stoop and pick them out the moment before eating them; and as they were often cooked on the table, their perfect freshness was thus insured. Martial (Lib. X., Epigram. XXX., vv. 16-25) alludes to this custom, as well as to the culture and taming of fish in the piscina.

"Nec seta largo quaerit in mari praedam,
Sed e cubiclo lectuloque jactatam
Spectatus alte lineam trahit piscis.
Si quando Nereus sentit Aeoli regnum,
Ridet procellas tula de suo mensa.
Piscina rhombum pascit et lupos vernas,
Nomenculator mugilem citat notum
Et adesse jussi prodeunt senes mulli."

It having been remarked that the red mullet passed through many changes of color in dying, like the dolphin, fashion decreed that it should die upon the table. Served alive, inclosed in a glass vessel, it was cooked in the presence of the attentive guests, by a slow fire, in order that they might gloat upon its sufferings and expiring hues, before satisfying their appetites with its flesh.

It will not surprise us to learn that the eminent gourmand Apicius offered a prize to the inventor of a new sauce made of mullets' livers.

But we may remark, that fish, like all other natural objects, were studied by the ancients only to pet or to eat. All their views of Nature were essentially selfish; none were disinterested, reverential, deductive, or scientific. Nature ministered only to their appetites, in her various kinds of food,—to their service, in her beasts of burden,—or to their childish or ferocious amusement, with talking birds, as the starling, with pet fish, or with pugnacious wild beasts. There was no higher thought. The Greeks, though fond of flowers, and employing them for a multitude of adornments and festive occasions entirely unequalled now, yet did not advance to their botanical study or classification. The Roman, if enamored of the fine arts, could see no Art in Nature. There was no experiment, no discovery, and but little observation. The whole science of Natural History, which has assumed such magnitude and influence in our times, was then almost entirely neglected.

And yet what an opportunity there was for the naturalist, had a single enthusiast arisen? All lands, all climes, and all their natural productions were subservient to the will of the Emperor. The orb of the earth was searched for the roe of eels or the fins of mullets to gratify Caesar. And the whole world might have been explored, and specimens deposited in one gigantic museum in the Eternal City, at the nod of a single individual. But the observer, the lover of Nature, was wanting; and the whole world was ransacked merely to consign its living tenants to the vivaria, and thence to the fatal arena of the amphitheatre. Yet even here the naturalist might have pursued his studies on individuals, and even whole species, both living and dead, without quitting Rome. The animal kingdom lay tributary at his feet, but served only to satiate his appetite or his passions, and not to enrich his mind.

So, again, Rome's armies traversed the globe, and her legions were often explorers of hitherto unknown regions. But no men of science, no corps of savans was attached to her cohorts, to march in the footsteps of conquest and gather the fruits of victory to enrich the schools. Provinces were devastated, great cities plundered, nations made captive, and all the masterpieces of Art borne off to adorn Rome. But Nature was never rifled of her secrets; nor was discovery carried beyond the most material things. The military spirit stifled natural science.

There were then, to be sure, no tendencies of thought to anything but war, pleasure, literature, or art. There was comparatively no knowledge of the physical sciences, whose culture Mr. Buckle has shown to have exerted so powerful an influence on civilization. The convex lens—as since developed into the microscope, the giver of a new world to man—was known to Archimedes only as an instrument to burn the enemy's fleet.

* * * * *

Modern pisciculture in some measure imitates, although, it does not rival the ancient. Many methods have been devised in France and England of breeding and nurturing the salmon, the trout, and other valuable fish, which are annually becoming more scarce in all civilized countries. But all this is on a far different principle from that pursued at Rome. We follow pisciculture from necessity or economy, because fish of certain kinds are yearly dying out, and to produce a cheap food; but the Romans followed it as a luxury, or a childish amusement, alone. And although our aldermen may sigh over a missing Chelonian, as Crassus for his deceased eel, or the first salmon of the season bring a fabulous price in the market, yet the time has long passed when the gratification of appetite is alone thought of in connection with Nature. We know that living creatures are to be studied, as well as eaten; and that the faithful and reverent observation of their idiosyncrasies, lives, and habits is as healthful and pleasing to the mind as the consumption of their flesh is wholesome and grateful to the body. The whole science of Zoölogy has arisen, with its simple classifications and its vast details. The vivaria of the Jardin des Plantes rival those of the Colosseum in magnitude, and excel them in object. Nature is ransacked, explored, and hunted down in every field, only that she may add to the general knowledge. Museums collect and arrange all the types of creative wisdom, from the simple cell to man. Science searches out their extinct species and fossil remains, and tells their age by Geology. The microscope pursues organic matter down into an infinity of smallness, proportionately as far as the telescope traces it upwards in the infinity of illimitable space. Last of all, though not till long after the earth and the air had been seemingly exhausted, the desire of knowledge began to push its way into the arcana of the sea,—that hidden half of Nature, where are to be found those wonders described by Milton at the Creation,—where, in obedience to the Divine command,

"Be fruitful, multiply, and in the seas
And lakes and running streams the waters fill, …
Forthwith the sounds and seas, each creek and bay,
With fry innumerable swarm, and shoals
Of fish, that with their fins and shining scales
Glide under the green wave in sculls that oft
Bank the mid sea: part single or with mate
Graze the sea-weed, their pasture, and through groves
Of coral stray, or sporting with quick glance
Show to the sun their waved coats dropt with gold,
Or in their pearly shells at ease attend
Moist nutriment, or under rocks their food
In jointed armor watch."

But no means were at hand to pursue these unknown creatures to their unknown residences, and to observe their manners when at home. Single, withered, and often mutilated specimens of minute fish, mollusks, or radiata, in the museum, alone illustrated the mysteries of the deep sea. Fish, to be sure, could be kept for longer or shorter periods in globes of glass filled with water; but the more delicate creatures inevitably perished soon after their removal from their mysterious abodes. Such a passionate desire to "search Nature and know her secrets" finally originated the idea of the Aquarium.

The term vivarium was used among the ancients to signify many things,—from the dens of the wild animals which opened under the Colosseum, to an oyster-bed; and so now it may mean any collection of living creatures. Hence it could convey no distinct idea of a marine collection such as we propose to describe. The term aqua was added to express the watery element; but the compound aqua-vivarium was too clumsy for frequent employment, and the abbreviated word aquarium has come into general use.

Thus the real Aquarium is a water-garden and a menagerie combined,—and aims to show life beneath the waters, both animal and vegetable, in all the domestic security of its native home, and in all the beauty, harmony, and nice adaptation of Nature herself. It is no sudden discovery, but the growth of a long and patient research by naturalists.

"What happens, when we put half a dozen gold-fish into a globe? The fishes gulp in water and expel it at the gills. As it passes through the gills, whatever free oxygen the water contains is absorbed, and carbonic acid given off in its place; and in course of time, the free oxygen of the water is exhausted, the water becomes stale, and at last poisonous, from excess of carbonic acid. If the water is not changed, the fishes come to the surface and gulp atmospheric air. But though they naturally breathe air (oxygen) as we do, yet they are formed to extract it from the water; and when compelled to take air from the surface, the gills, or lungs, soon get inflamed, and death at last puts an end to their sufferings.

"Now, if a fish-globe be not overcrowded with fishes, we have only to throw in a goodly handful of some water-weed,—such as the Callitriche, for instance,—and a new set of chemical operations commences at once, and it becomes unnecessary to change the water. The reason of this is easily explained. Plants absorb oxygen as animals do; but they also absorb carbonic acid, and from the carbonic add thus absorbed they remove the pure carbon, and convert it into vegetable tissue, giving out the free oxygen either to the water or the air, as the case may be. Hence, in a vessel containing water-plants in a state of healthy growth, the plants exhale more oxygen than they absorb, and thus replace that which the fishes require for maintaining healthy respiration. Any one who will observe the plants in an aquarium, when the sun shines through the tank, will see the leaves studded with bright beads, some of them sending up continuous streams of minute bubbles. These beads and bubbles are pure oxygen, which the plants distil from the water itself, in order to obtain its hydrogen, and from carbonic acid, in order to obtain its carbon."[45 - The Book of the Aquarium, by Sidney Hibbert.]

Thus the water, if the due proportion of its animal and vegetable tenants be observed, need never be changed. This is the true Aquarium, which aims to imitate the balance of Nature. By this balance the whole organic world is kept living and healthy. For animals are dependent upon the vegetable kingdom not only for all their food, but also for the purification of the air, which they all breathe, either in the atmosphere or in the water. The divine simplicity of this stupendous scheme may well challenge our admiration. Each living thing, animal or plant, uses what the other rejects, and gives back to the air what the other needs. The balance must be perfect, or all life would expire, and vanish from the earth.

This is the balance which we imitate in the Aquarium. It is the whole law of life, the whole scheme of Nature, the whole equilibrium of our organic world, inclosed in a bottle.

For the rapid evolution of oxygen by plants the action of sunlight is required. That evolution becomes very feeble, or ceases entirely, in the darkness of the night. Some authorities assert even that carbonic acid is given off during the latter period. So, too, they claim that there are two distinct processes carried on by the leaves of plants,—namely, respiration and digestion: that the first is analogous to the same process in animals; and that by it oxygen is absorbed from, and carbonic acid returned to the atmosphere, though to a limited degree: and that digestion consists in the decomposition of carbonic acid by the green tissues of the leaves under the stimulus of the light, the fixation of solid carbon, and the evolution of pure oxygen. The theory of distinct respiration has been somewhat doubted by the highest botanical authority of this country; but the theory of digestion is indisputable. And it is no less certain that all forms of vegetation give to the air much more free oxygen than they take from it, and much less carbonic acid, as their carbonaceous composition shows. If fresh leaves are placed in a bell-glass containing air charged with seven or eight per cent. of carbonic acid, and exposed to the light of the sun, it will be found that a large proportion of the carbonic acid will have disappeared, and will be replaced by pure oxygen. But this change will not be effected in the dark, nor by any degree of artificial light. Under water the oxygen evolved from healthy vegetation can be readily collected as it rises, as has been repeatedly proved.

Why carbonic acid is, to a limited degree, given off by the plant in the night, is merely because the vital process, or the fixation of carbon and evolution of oxygen, ceases when the light is withdrawn. The plant is only in a passive state. Ordinary chemical forces resume their sway, and the oxygen of the air combines with the newly deposited carbon to reproduce a little carbonic acid. But this must be placed to the account of decomposing, not of growing vegetation; for by so much as plants grow, they decompose carbonic acid and give its oxygen to the air, or, in other words, purify the air.

It has been found by experiment, that every six pounds of carbon in existing plants has withdrawn twenty-two pounds of carbonic acid gas from the atmosphere, and replaced it with sixteen pounds of oxygen gas, occupying the same bulk. And when we consider the amount of carbon that is contained in the tissues of living, and of extinct vegetation also, in the form of peat and coal, we may have some idea of the vast body of oxygen which the vegetable kingdom has added to the atmosphere.

And it is also to be considered, that this is the only means we know of whereby free oxygen is given to supply the quantity constantly consumed in respiration, combustion, and other vast and endless oxygen-using processes. It follows, therefore, that animals are dependent upon plants for their pure oxygen, as well as for their food. But the vegetable kingdom might exist independently of the animal; since plants may derive enough carbon from the soil, enriched by the decaying members of their own race.

There is, however, one exception to the law that plants increase the amount of oxygen in the air. During flowering and fruiting, the stores of carbon laid up in the plant are used to support the process, and, combining with the oxygen of the air, both carbonic acid and heat are given off. This has been frequently proved. In large tropical plants, where an immense number of blossoms are crowded together, the temperature has risen twenty to fifty degrees above that of the surrounding air.

As most of the aquatic plants are cryptogamous, or producing by spores, and not by flowers, it seems probable that the evolution of carbonic acid and heat is much less in degree in them, and therefore less in the water than in the air. We may, therefore, venture to lay it down as a general principle, that plants evolve free oxygen in water, when in the sunlight, and remove the carbonic acid added to the water by the respiration of the animals.

But since this is a digestive or nutritive process, it follows that aquatic plants may derive much or all of their food from the water itself, or the carbon in it, in the same manner as the so-called air-plant, which grows without soil, does from the air. It is true, at any rate, that, in the fresh-water aquarium, the river and brook plants need no soil but pebbles; and that the marine plants have no proper root, but are attached by a sort of sucker or foot-stalk to stones and masses of rock. It is very easy to see, then, how the aquarium may be made entirely self-supporting; and that, excepting for the larger carnivorous fish, who exhaust in a longer or shorter period the minute creatures on which they live, no external food is required.

A very simple experiment will prove the theory and practicability of the aquarium. In a glass jar of moderate size was placed a piece of Ulva latissima, or Sea-Lettuce, a broad-leaved, green, aquatic plant, and a small fish. The mouth was closed by a ground glass stopper. The jar was exposed to the light daily; the water was never changed; nor was the glass stopper removed, excepting to feed the fish, once or twice a week, with small fragments of meat. At the end of eight months both remained flourishing: the fish was lively and active; and the plant had more than half filled the bottle with fresh green leaves.

Any vessel that will hold water can, of course, be readily converted into an aquarium. But as we desire a clear view of the contents at all times, glass is the best material. And since glass globes refract the light irregularly and magnify and distort whatever is within them, we shall find an advantage in having the sides of the aquarium parallel and the form rectangular. As the weight of the aquarium, when filled with water, is enormous,—far more than we should at first imagine,—it follows that it must be capable of resisting pressure both from above and from within. The floor and stand, the frame and joints must be strong and compact, and the walls of plate or thick crown glass. The bottom should be of slate; and if it is designed to attach arches of rock-work inside to the ends, they, too, must be of slate, as cement will not stick to glass. The frame should be iron, zinc, or well-turned wood; the joints closed with white-lead putty; the front and back of glass. There is one objection to having the side which faces the light of transparent glass, and that is that it transmits too much glare of sunlight for the health of the animals. In Nature's aquarium the light enters only from above; and the fish and delicate creatures have always, even then, the shady fronds of aquatic plants or the shelter of the rocks,—as well as the power of seeking greater depths of water, where the light is less,—to protect themselves from too intense a sunshine. It is, therefore, sometimes advisable to have the window side of the aquarium made of glass stained of a green color. It is desirable that all aquarial tanks should have a movable glass cover to protect them from dust, impure gases, and smoke.

When we speak of an aquarium, we mean a vessel holding from eight to thirty gallons of water. Mr. Gosse describes his larger tank as being two feet long by eighteen inches wide and eighteen inches deep, and holding some twenty gallons. Smaller and very pretty tanks may be made fifteen inches long by twelve inches wide and twelve deep. Great varieties in form and elegance may be adapted to various situations.

There are two kinds of aquaria, the fresh- and the salt-water: the one fitted for the plants and animals of ponds and rivers; the other for the less known tenants of the sea. They are best described as the River and the Marine Aquarium, and they differ somewhat from each other. We shall speak first of the fresh-water aquarium.

The tank being prepared, and well-seasoned, by being kept several weeks alternately full and empty, and exposed to the sun and air, so that all paint, oil, varnish, tannin, etc., may be wholly removed, the next thing is to arrange the bottom and to plant it. Some rough fragments of rock, free from iron or other metals that stain the water, may be built into an arch with cement, or piled up in any shape to suit the fancy. The bottom should be composed entirely of shingle or small pebbles, well washed. Common silver sand, washed until the water can be poured through it quite clear, is also suitable.

Mould, or soil adapted to ordinary vegetation, is not necessary to the aquatic plants, and is, moreover, worse than useless; since it necessitates the frequent changing of the water for some time, in order to get rid of the soluble vegetable matter, and promotes the growth of Confervae, and other low forms of vegetation, which are obnoxious.

Aquatic plants of all kinds have been found to root freely and flourish in pebbles alone, if their roots be covered. The plants should be carefully cleared of all dead parts; the roots attached to a small stone, or laid on the bottom and covered with a layer of pebbles and sand.

The bottom being planted, the water may be introduced through a watering-pot, or poured against the side of the tank, so as to avoid any violent agitation of the bottom. The water should be pure and bright. River-water is best; spring-water will do, but must be softened by the plants for some days before the fishes are put in.

Sunshine is good for the tank at all seasons of the year. The fresh- requires more than the salt-water aquarium. The amount of oxygen given off by the plants, and hence their growth and the sprightliness of the fishes, are very much increased while the sun is shining on them.

In selecting plants for the aquarium some regard is to be paid to the amount of oxygen they will evolve, and to their hardiness, as well as to their beauty. When it is desired to introduce the fishes without waiting long for the plants to get settled and to have given off a good supply of oxygen, there is no plant more useful than the Callitricke, or Brook Star-wort. It is necessary to get a good supply, and pick off the green heads, with four or six inches only of stem; wash them clean, and throw them into the tank, without planting. They spread over the surface, forming a rich green ceiling, grow freely, and last for months. They are continually throwing out new roots and shoots, and create abundance of oxygen. Whenever desired, they can be got rid of by simply lifting them out.

The Vallisneria, or Tape-Grass, common in all our ponds, is essential to every fresh-water tank. It must be grown as a bottom-plant, and flourishes only when rooted. The Nitella is another pleasing variety. The Ranunculus aquatilis, or Water-Crowfoot, is to be found in almost every pond in bloom by the middle of May, and continues so into the autumn. It is of the buttercup family, and may be known as a white buttercup with a yellow centre. The floating leaves are fleshy; the lower ones finely cut. It must be very carefully washed, and planted from a good joint, allowing length enough of stem to reach the surface. Some of the blossom-heads may also be sprinkled over the surface, where they will live and bloom all through the summer. The Hydrocharis, or Frog's-Bit, and the Alisma, or Water-Plantain, are also easily obtained, hardy and useful, as well as pleasing. Many rarer and more showy varieties may be cultivated; we have given only the most common and essential. All the varieties of Chara are interesting to the microscopist, as showing the phenomenon of the circulation of the sap, or Cyclosis.

Of the living tenants of the aquarium, those most interesting, as well as of the highest organization, are the fishes. And among fishes, the family of the Cyprinidae are the best adapted to our purpose; for we must select those which are both hardy and tamable. Cyprinus gibelio, the Prussian Carp, is one of the best. It will survive, even if the water should accidentally become almost exhausted of oxygen. It may be taught, also, to feed from the hand. None of the carp are very carnivorous. Cyprinus auratus, or the Gold-fish, is one of the most ornamental objects in an aquarium. But the Minnow, C. phoxinus, is the jolliest little fish in the tank. He is the life of the collection, and will survive the severest trials of heat and cold. The Chub, a common tenant of our ponds, is also a good subject for domestication. The Tench and Loach are very interesting, but also very delicate. Among the spiny-finned fishes, the Sticklebacks are the prettiest, but so savage that they often occasion much mischief. For a vessel containing twelve gallons the following selection of live stock is among those recommended: Three Gold Carp, three Prussian Carp, two Perch, four large Loach, a dozen Minnows, six Bleak, and two dozen Planorbis. Some varieties of the Water-Beetles, or Water-Spiders, which the fishes do not eat, may also well be added. The Newt, too, is attractive and harmless.