Some scientists believe that the total number of fish species in the world’s waters is very large and reaches 40,000. Approximately 25,000 fish species are already classified and have scientific names. However, it is known that the total number of fish species on our planet, taking into account those that live in the oceans and remote freshwater bodies, is much larger.
Approximately 8,500 species of freshwater fish have already been described, while others, although known, have not yet been classified. Some of these fish are already kept in their aquarists.
About 2000 species of tropical freshwater fish are available for people who have chosen aquarism as a hobby. There are plenty to choose from!
Initially, your choice of fish will probably be based on their appearance. Visiting the pet store, you will see representatives of many species of fish. However, to get the best idea of the types of fish available, it is best to look at illustrated editions.
Be careful and remember that not all types of fish whose images you find in books or magazines are commercially available in your area or even in your country, so you may have to put them on your wish list for the future.
At the same time keep in mind that the appearance of the fish – this is not all. One important lesson should be learned from the beginning.
The fact is that there are other factors that are important when choosing the type of fish for your tank, no matter what you plan: the initial settlement of the aquarium or subsequent additions.
It is important to remember that fish species, like mammals and birds, are numerous and distinguished by great diversity. There are few people who would keep a lion together with a gerbil or an eagle together with a budgie at their home. Lovers usually do not even think to keep a lion or an eagle!
Nevertheless, countless aquarists make this mistake again and again and try to keep the same predators, but only with fins, in the same aquarium with completely harmless fish or trying to keep in themselves fish that really have no place in the home aquarium. Some fish are dangerous, for example Piranha Serrasalmus spp. and electric eel Electrophorus spp., while others, such as the red-tailed catfish Phractocephalus hemioliopterus, as well as the packs Piaractus, Colossoma spp., are simply too large.
It is quite clear that you will be surprised when you find out that someone may be so unwise to buy fish that are too big for their aquarium. The problem here is that when the fish are sold, they are usually still very small. Most fish that you find on sale will be approximately 2.5 to 10.0 cm long.
However, when some of them become adults or almost adults, other fish next to them will seem like real babies. After all, the little lion cub is still more than an adult domestic cat!
You may also be surprised by the fact that dangerous fish, or too large, or those that cannot be kept together with other fish, are generally commercially available. Indeed, there is such a point of view that the sale of fish that are considered unsuitable for domestic aquariums should be banned altogether, and this opinion is becoming increasingly popular.
However, some people believe that this would be an infringement of personal freedom: there are experienced aquarists who have suitable conditions and are fully capable of properly maintaining such “problem” fish. If there were only those fish that could be held together, then aquarism would not be interesting for us and would not bring so much pleasure.
The aquarist’s task is to learn as much as possible about the types of fish he is going to buy and make an informed and informed decision whether these fish are suitable for his aquarium and whether they can become good neighbors for fish already existing or planned for acquisition in the future. “First find out everything!” – this is one of the basic rules for keeping fish.
The following are some of the reasons why a particular type of fish may not be suitable for a particular aquarium.
The fish is too big for this tank (either at the moment or when it grows up).
The fish is too large (either at the moment or when it grows up) compared to the rest of the fish that inhabit the aquarium. Even if a large fish does not eat smaller ones (see below), still smaller fish are likely to fear for their lives if there is a much larger fish in the same aquarium.
A fish, even an adult, is too small to live with the rest of the fish that inhabit the aquarium.
The fish is territorial and it needs more personal space than the size of the aquarium allows.
The fish is predatory, that is, it eats other, smaller fish. This behavior is quite natural for fish whose diet in the wild consists of other fish. Many omnivorous fish also eat other fish, much smaller than themselves.
However, this does not mean that predatory and omnivorous fish cannot be kept together with other fish – these others simply should not be too small.
The fish is so small that it can be eaten by other fish already present in the aquarium.
Fish bites off other people’s fins. This is usually not a problem if you do not keep other fish with long, seductive fins in the same aquarium.
Or, on the contrary, the fish itself has long, seductive fins, against which the fish already in the aquarium that have the habit of biting other people’s fins cannot resist.
The fish is too brisk and cannot get along with calm or too nervous fish, and vice versa.
Fish eats aquatic plants.
Fish buried in the ground. There is nothing wrong with that, but an aquarist may not wish to redo the interior of the aquarium again.
Fish require fundamentally different environmental factors – the chemical composition of the water, its movement and temperature, lighting, and shelter – compared to other fish already present in the aquarium.
All this, of course, can be adapted in such a way that it is suitable for this fish, but only on condition that changes in the environment are also suitable for its aquarium mates. It is very important to consider all these elements in general connection. If all the fish are about the same size, this does not mean that they are compatible.
Even if the fish is small, but it definitely needs its own territory, it can still cause significant confusion in the aquarium. Fish of two different species may require water of the same chemical composition, temperature and light, but they may be completely incompatible with respect to such a parameter as the movement of water if one of them lives in nature in slow water currents, and the other in turbulent flows.
A very common mistake is to assume that if these types of fish are sympatric (that is, they can be together in nature), then they can be kept together in captivity. Most biotopes (part of the habitat of animals and plants, characterized by relatively homogeneous conditions. – Note. Lane) are inhabited by both large and small species – there are both predators and their prey. Another common mistake is to assume that individuals of the same species will necessarily get along well together.
In many cases, especially when it comes to males, they see each other as rivals and can fight each other. The same applies to representatives of related species with similar shape and color.
In contrast, representatives of species of fish living in flocks in natural conditions, necessarily need a society of their own kind. When fish gather in shoals, this is for them a way to protect against predators.
If a fish belongs to such a species and in captivity it is deprived of such a security measure, it will be nervous and under stress.
Some species of bottom fish – for example, the Corydoras corridor and some of the loachworm – also live in groups. The reasons for this behavior are not yet fully understood, but such fish seem to feel better if they are provided with a society of their own kind.
The term “unpretentious fish” usually refers to species of fish that can survive in any environmental conditions. Such fish can be hardy from birth if in the wild they had to adapt to changing water characteristics or to bad quality water. Maybe they just acclimatized to life in an aquarium, somehow survive in these conditions – and nothing more.
Even the most acclimatized fish feel much better and show a brighter color if kept in conditions as close as possible to the natural ones.
In nature, representatives of the family of the petsilia (for example, the guppy Poecilia reticulata), many, but not all labyrinth fish, and also the hirinoheylus, or the warrior-eating Siamese Gyrinocheilus aymonieri belong to the undemanding.
Among the unpretentious fish acclimatized in captivity are neon Paracheirodon innesi and pelvic chromis vulgaris, or the parrot Pelvicachromis pulcher. Some fish, caught in natural conditions (and not specially bred for sale), lived in nature in special conditions, but survive in captivity even in an inappropriate environment. Such fish can also be considered unpretentious.
Among them are many types of catfish, as well as red neon Paracheirodon axelrodi and many tetras. And finally, some species of fish are usually considered hardy, as they are bred for commercial purposes and sold in most pet stores, although in fact they are not at all unpretentious.
A classic example is the apistogram of Ramirez Microgeophagus ramirezi.
So, we advise you to carefully familiarize yourself with the origin of the fish, even if it is considered that it is unpretentious, at least so that you can be completely sure of it. In addition, remember that if a fish is caught in nature, then it is not acclimatized to life in captivity, even if many other members of the same species, divorced in an aquarium, have long been acclimatized.
A very common mistake is to assume that all undemanding fish are compatible with each other. Endurance means only that such fish are likely to survive, whatever conditions you create for them, but this does not mean that they will not grow in size, devour each other, eat plants, fight, etc.
An aquarium can hold only a limited number of fish. It is usually calculated by determining the total length of all fish in relation to the surface area of the water in the aquarium, although for some fish species other criteria are used. It is important to remember that the “density of landing” is calculated depending on the total length of the fish when they are adults.
But when you buy fish, most of them will not be fully developed yet. Overcrowding in an aquarium can cause stress in fish and lead to numerous health problems.
The best source of information is literature on aquarium fish, among which you can find encyclopedic catalogs of fish species, as well as specialized works on specific groups. If you have to deal with the type of fish that were not previously contained in aquariums, you must read the literature on their natural habitat in order to create appropriate conditions for them in captivity. Nevertheless, it is better to let experienced aquarists who are familiar with the artificial creation of specialized biotopes deal with such fish.
They usually have always ready free aquariums in case a special room is needed.
Other amateur aquarists can also provide useful information. However, in any case, it is worthwhile to get acquainted with the relevant literature, unless you are absolutely sure that the aquarist who gives you advice is a qualified and conscientious specialist.
Maybe many aquarists manage to save fish life, but this does not mean that they contain them as expected.
Pet stores can be an invaluable source of information. However, unfortunately, some owners or employees from the staff of such stores may intentionally mislead a careless aquarist to sell their goods.
If you are not sure about the honesty of the seller, then read the literature before you make a purchase.
Any incompatibility situation – between individual fish or between fish and the environment – usually causes stress, which in turn can lead to serious illnesses.