Special Purpose Aquariums

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This category includes:

- breeding aquariums, often a simple glued glass tank with no soil, for temporary use;

- hospital-aquariums;

- large aquariums. These are large by virtue of their length, as their depth and breadth cannot exceed certain limits for technical and practical reasons. They sometimes present installation problems, due to the weight on the base and the special materials required for their construction.

Large tanks are often given over to large species which require ample living space on account of their size. They can also be used for the other purposes mentioned above, because it is generally considered that the bigger the aquarium, the easier it is to maintain its equilibrium. Contrary to what is often thought, their maintenance does not imply more problems if an equilibrium is really achieved.


In public aquariums, fishkeeping takes on a new dimension. The general trend is to offer the public extremely large tanks, in which the behavior of the animals reflects as closely as possible what actually goes on in their natural habitat, usually beyond the reach of most people. These "living museums" serve not only to present aquatic animals but also to study them, as much still remains to be discovered about some biological phenomena (for example, the reproduction of marine fish). This new generation of "real conditions" aquariums includes among its ranks the Deep-Sea World in Fife, Scotland, the Fenit Sea World in County Kerry, Ireland, and the Clearwater Marine Aquarium in Florida, not forgetting illustrious precursors such as the National Aquarium in Washington and the Belle Isle Aquarium, Detroit, which opened in 1873 and 1904, respectively.

There are now literally hundreds of public aquariums in both Europe and North America, some of which specialize in the fauna of their local region, such as the recently opened aquarium in Touraine, France, the largest in Europe. Space does not permit an exhaustive list, but readers can obtain information about public aquariums from the Fish Information Service (FINS) (www.actwin.com/fish/public.cgi).

Freshwater room in the tropical aquarium in Tours. •

Tropical lagoon tank in La Rochelle aquarium. •

There are more than 30,000 species offish, more or less evenly distributed between fresh water and sea water, and of these some 1,500 are of interest to the aquarist. Fish embody a great anatomical and biological diversity and richness, and this can be clearly seen in aquariums.


Whatever type of aquarium you choose, a minimal knowledge of the anatomy and biology of the species you are raising is an essential prerequisite. The information below, presented in layman's language, allows you to keep your fish in good health, in the best possible conditions, to feed them appropriately so that they can grow, and to facilitate their reproduction — in short, to understand them better in order to take better care of them.


Hippocampus A fish is typically drawn as an elongated kuda. spindle, and in fact this is the most common form, as it makes it easier to swim in open water. These hydro-dynamic characteristics permit rapid acceleration and not inconsiderable speeds (sometimes up to 20 km per hour) in a medium (water) that offers a certain degree of resistance. However, there are other forms, that are also all connected with the lifestyle of the fish in question: bottom-dwellers have

• Pterois volitans.

a flat stomach, while those that live in water obstructed by plants and branches have compact, thin bodies that enable them to squeeze through the obstacles. This is equally the case with the countless fish in the coral reefs, which thread their way through the blocks of coral. Finally, there are certain fish that are unclassifi-able, so varied and strange are the forms they flaunt, although they always correspond to a particular lifestyle.

The fins

Fish have several types of fins, each one playing a precise role. Their forms and names are often used to classify them into different families.

Of the unpaired fins (i.e. consisting of a single fin), the most noteworthy are the dorsal and the anal fins. These serve to stabilize the fish when it is not going very fast or is coming to a halt, and they are tucked in when the fish swims more quickly. The caudal fin (incorrectly referred to as the tail) supplies propulsion, in conjunction with the rear part of the body. In some species, particularly the Characins and the catfish, there is a small extra fin between the dorsal and the caudal fins, known as the adipose fin.

although this is not really used. The paired fins, attached symmetrically to each side of the body, are called pectoral and pelvic fins. They are used for stabilizing, stopping, slowing down, or changing direction: vertically, from the water surface to the bed, and vice versa, from side to side, from left to right, from right to left. Fins consist of a membrane stretched on spokes, and they can all be tucked in along the body, with the exception of the caudal fin. The adipose fin is merely a fold of skin, without any spokes. When the spokes are longer than the fins they are known as spiny fins, and they can represent a danger to the aquarist, as in the case of the scorpion fish, for example.

The mucus, skin, and scales

Fishes' bodies are covered with a mucus that plays a double role: it reinforces the hydrodynamics by "smoothing" the skin, and it affords protection against the penetration of parasites or pathogenic elements. The latter point is extremely important, and it explains why fish must not be moved by hand: this risks damaging the mucus and facilitating the development of certain diseases.

Contrary to a widely held belief, the scales do not stick out of the body but are an integral part of the skin, and they are visible through a fine layer of transparent epidermis. When a scale is raised, damaged, or torn off, the skin itself is equally affected and becomes vulnerable to the action of pathogens.


Every fish has a basic coloring that can be modified. Their shiny, metallic appearance, derived from the crystals present in the cells of the skin, varies according to

Male fighting fish (Betta splendens).


Male fighting fish (Betta splendens).


Some aquarium fish have fins that are very different in shape or size from those that are found in nature. They are the result of patient breeding carried out by aquarists over a period of years. The visual effect is guaranteed, but the fish's behavior is sometimes altered, especially its velocity when moving around. Fish with large fins in the form of sails have little more than a remote relationship with their wild cousins, which have gone out of fashion and are no longer to be seen in tanks. The purpose of these selections can sometimes be in doubt: they undeniably result in highly attractive fish, but what advantage do they have over other stunning natural specimens?

Xipho (Xiphophorus helleri), bred with overdeveloped fins. •

the direction of the light striking them. A fish's color is a result of the different pigments located in the epidermis. These can change, slowly, for reproduction and camouflage, under the control of hormones, or more quickly, for flight or aggression,

Xipho (Xiphophorus helleri), bred with overdeveloped fins. •

Somespecies of fish are protected by the bony plates covering their head and body

Euxiphipops navarchus.



The black bands of the scalare enable it to hide.

The coloring of a fish varies according to its age and mood. Some fish living in coral reefs reject individuals of their own species or a related species with a coloring similar to their own (Pomacanthids, also known as angelfishes, for example) because they consider newcomers as enemies wishing to appropriate their territory and their food supply. This is why their offspring have a very different coloring from that of adults, so as not to be considered intruders. In their desire to protect themselves, some fish adopt a camouflage to merge in with their surroundings, or, in contrast, reduce the intensity of their color to pass unnoticed. Thus, the vertical black stripes on the scalare allow it to hide among submerged branches and plants (see drawing above). In some species, the male and female sport very different colorings, enabling them to be distinguished - a gift of nature much appreciated by aquarists! This is true of a large number of the Cichlids in the African lakes. At mating time, the male can flaunt vivid colors, not only to seduce the female in the courting ritual but also to impress his rivals and scare them off. This occurs with the meeki, a Central American Cichlid - the underside of its head turns red at mating time.

The coloring of fish exists not merely to satisfy the eye; it plays anequally important social role. •

Certain fish, such as this murena, have very sharp teeth, indicating that they are predators.

controlled by nerves. The coloring of a fish can also vary when it is suffering from disease or nutrient deficiency.

The head

Whatever its form - conical, elongated, or stocky - the head houses some important organs:

- first of all, there are the which have no eyelids and are highly mobile. This mobility, coupled with their position on the side of the head, allows a fish to command a broad field of vision - around 270°. In contrast, the clarity of its vision is unexceptional: beyond a certain distance, it distinguishes masses and forms rather than details. Fish are very sensitive to variations in light - detecting low intensities of light, such as that of the moon - and they can recognize colors.

- next comes the mouth, with a size and shape related to its feeding habits. Carnivorous fish generally have a large mouth that can open wide and is endowed with an array of pointed teeth, which are sometimes curved towards the back to keep hold of their prey. Omnivorous and herbivorous fish have a smaller mouth, with flat teeth ideally suited to grinding food.

•Fish have a particularlywide field of vision

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The COMPLETE guide to Aquariums

The COMPLETE guide to Aquariums

The word aquarium originates from the ancient Latin language, aqua meaning water and the suffix rium meaning place or building. Aquariums are beautiful and look good anywhere! Home aquariums are becoming more and more popular, it is a hobby that many people are flocking too and fish shops are on the rise. Fish are generally easy to keep although do they need quite a bit of attention. Puppies and kittens were the typical pet but now fish are becoming more and more frequent in house holds. In recent years fish shops have noticed a great increase in the rise of people wanting to purchase aquariums and fish, the boom has been great for local shops as the fish industry hasnt been such a great industry before now.

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