Xiphophorus hellerii, Grön
Swordtail

Here it is stated from which continent a particular species originates. The whole continent is admittedly marked, but this does not usually mean that the species lives in the entire marked area.
It is more probable that it is only found in a small area such as at a small reef in a special lake, in a larger river area, etc. For more details of the area, see "Natural" on each fish description.

Different fish species require different sizes of aquarium. What affects this is, of course, primarily the size of the fish, but there is also something else. Active fish that swim a lot require a larger aquarium than a more passive one, and so on.

We have given a figure both for the minimum length of the aquarium and for its minimum content in liters. These two numbers are often followed, but not always. Above all, very active fish want relatively long aquariums because they swim a lot and then need a large swimming space. Other rather passive but large fish species may eat a lot and then a large liter content is required because it is easier to maintain a biological balance in such an aquarium.

As a rule, however, the two measures are followed. Our statement can only be seen as an approximate starting point for how small an aquarium can be. A larger aquarium is never wrong and it is always easier to maintain and find a biological balance the larger an aquarium is.

In nature, different fish species live in different waters that maintain different temperatures. Most often, tropical fish are found in our aquariums, which means that they want fairly warm water. However, the water temperature can vary during the year even in tropical waters. Unlike humans, fish are warm-blooded animals, which means that their body temperature follows fluctuations in water temperature. Therefore, it is especially important that we have the right temperature for the aquarium water.

Species that live in water where there are large fluctuations in temperature between different seasons are naturally less sensitive to temperature variations than those that live in water where the temperature is about the same all year round.

The temperatures we have specified for each species indicate within which range the temperature must remain in the aquarium for the fish to thrive.

pH is a measure of the acidity and alkalinity of the water and is measured on a scale from 0 to 14 where pH 7 stands for neutral water, above 7 is basic (alkaline) and below 7 is acidic. The pH value is determined by whether the matter (eg minerals, organic matter) that has dissolved in the water is alkaline or acidic and by the amount of dissolved matter.

Different species live in nature in different kinds of water. In South America and Asia the water is usually acidic (pH below 7) to neutral (around 7), in West Africa relatively neutral (around 7), in Central America and the deep-water lakes in East Africa are alkaline (above 7).

Therefore, it is important that the fish in the aquarium have approximately the same water. If you want to find out more about pH, such as how to measure, or how to change the pH value, There is alot of other information about different water chemical conditions you have to think about. For example, it is very important to know the KH value of water.

For each fish species, we have specified an interval within which the pH value must be in order for this particular species to thrive. Of course, through slow habituation, many species can get used to surviving in water values ​​that are outside this range, but it is definitely not recommended because it is partly a matter of animal cruelty and partly in the long run still risks taking an end with fright. Another important factor regarding the pH value is that it is kept stable, ie it must not vary too much, large jumps in the pH value (even if the upper and lower limit is within the range) are very harmful for many fish species.

Specifying the maximum length of a species is not the easiest thing to do. A species often becomes differently sized in nature and in an aquarium (usually larger in an aquarium environment), males and females are different sizes, and so on. When we calculated the length of a species, we started from normal adult size in the wild, as well as the largest of the female and male (usually the male, but far from always).

The length we specified can be quite different from the length they can achieve in an aquarium. An example of a genus that grows significantly larger in an aquarium is the Malawicylids in the genus Aulonocara. In nature they usually do not grow larger than 9 cm, in aquariums they often grow to 13-14 cm, ie 50% longer. The reason why a species becomes larger in an aquarium than in nature is the availability of food. In the aquarium, they get significantly more food, which they do not have to work (exercise) for, than they get in nature.

An example of the opposite is the Iridescent shark (Pangasius hypophthalmus) which in nature can be 130 cm, but which in an aquarium can be 80 cm, often not even that long. The reason for this is that the fish need space to grow to life size. If the aquarium is too small, it usually stays up in the plant.

Therefore, it is difficult to state an exact adult size, but the figure given is still an approximate starting point.

Different species are differently well adapted to life in an aquarium. Some species should not go into the aquarium. Based on our assessment, we have placed all species in different groups according to their degree of difficulty, with 1 as the easiest and 5 as the most difficult.

1 - Very hardy, peaceful and suitable beginner species.
2 - Relatively hardy and peaceful species that is normally easy to maintain.
3 - Suitable as an aquarium fish, but preferably read a book and / or talk to someone with experience of this species, to familiarize yourself with its special requirements.
4 - This species is difficult to keep in an aquarium and is only suitable for specialists who can offer the species the right conditions in a special aquarium.
5 - Clearly unsuitable as an aquarium fish. Usually due to the size and / or aggressiveness of the species.

The grading we have done obviously depends on our experience (and of the other aquarists we have consulted) of these particular fish. Other aquarists may have come to different conclusions, based on the conditions they had their fish under. These may also be right, although they may not have the same "rating" as we did.

Therefore, our "ratings" can be taken as a starting point when it comes to knowing how difficult a species is.

Fish usually eats what they are offered, but their intestinal system (long for herbivores, short for carnivores) can be damaged if they are fed with the wrong diet (especially for herbivores). Therefore, do not keep herbivores and carnivores together.

Carnivores - A species that mainly feeds on meat that can come from small invertebrates, snails, small fish, etc.

Omnivore - A species that can eat most things.

Herbivore - A species that eats high-fiber green food - usually algae, phytoplankton but sometimes aquarium plants

Carnivores and omnivores - An omnivore that mainly eats meat.

Herbivore and omnivore - An omnivore that mainly eats green.

SARF (Swedish Aquarium Associations National Association) runs a breeding campaign to encourage the breeding of aquarium fish. We can benefit from knowing the different breeding values ​​because they indicate the degree of difficulty for cultivating the fish you have.

More information about the breeding campaign can be found on SARF's website. The following levels are available - gold, silver and bronze - the fish that are shown with ? as a breeding value has not yet been placed at any level.

In addition, there is something called "elite". Some species have existed for a long time in Sweden but have never been breed and these have thus been given the epithet elite. As soon as someone has succeeded in breeding any of these species, the species is moved directly from "elite" to "gold". We choose to list the species that are now "elite" as "gold" because we do not have the opportunity to continuously update the changes that are taking place. For those who are interested in finding out which species are "elite", we encourage you to look at SARF's website.

En del arter behöver gömställen. Beroende av art kan gömställena bestå av grottor med stenar eller rötter, täta växtsnår, sand som de kan gräva ned sig i etc..

Vissa arter skall man ha en grupp av. Hur många som behövs varierar mellan olika arter (mellan 4-20).

En del arter behöver gömställen. Beroende av art kan gömställena bestå av grottor med stenar eller rötter,  täta växtsnår, sand som de kan gräva ned sig i etc..

Fisken måste gå ensam eller ensam inom sin art. Exempel är kampfiskhane som inte kan gå med andra hanar. Har man flera så kommer enbart en överleva då de är så aggresiva.

Fisken behöver mörkare områden i akvariet. Mycket bra sätt att uppnå det med kan vara dekoration eller växter. I synnerhet flytväxter kan vara bra för detta syfte.

Fiskar som hoppar måste ha ett tättslutande täckglas på akvariet. Tänk på att även täcka foderluckor och liknande. Hoppare hittar oftas ut i minsta lilla springa.

To make it clearer, we have tried to divide the different species into different groups. However, this division is in no way a scientific division, but more a practical one from a search and/or management point of view.

For each group, there is therefore a page with text and something/some photos where the group is described mainly based on how they are to be cared for.

If you choose to click on a special group, only the species that are placed in this group will be included. If you do not click on any group, all species will be included.

Some species live in freshwater that contains almost 0% salt, others in saltwater that contains a minimum of 3.5% salt (about 3.5 liters to 100 liters of water). Everything in between is brackish water. This applies to species that in the wild live in the end of rivers that flow into the sea. These species thrive best in brackish water.

All water is counted as brackish when it has a salinity of between 0-3.5%. In practice, however, one usually only talks about brackish water when the salinity is between 0.5% and 1.5%. Often when keeping brackish water fish in aquariums, the salinity is about 1.5%.

Some species migrate in nature, sometimes they go out to sea to spawn or vice versa and are therefore adapted to live in water with different salinity. These species are here in several different groups, sometimes perhaps in both fresh, brackish and salt water, others may thrive in both fresh and brackish water then they are set up there etc .

Therefore, if you click on e.g. you get brackish water with species that thrive in brackish water, but they can also be included in the salt water group and / or the fresh water group.

If you do not click on one, all species that thrive in freshwater will be included.

Different species live in nature in different kinds of water. In South America and Asia the water is usually acidic (pH below 7) to neutral (around 7), in West Africa relatively neutral (around 7), in Central America and the deep-water lakes in East Africa are alkaline (above 7).

Therefore, it is important that the fish in the aquarium get about the same water conditions. If you want to find out more about pH such as how to measure, or how to change the pH value, I urge you to go to the heading "Aquarium water" which you will find in the main column on the right.

If you are looking for one or more species that thrive best in either neutral, acidic or alkaline water, click on each. If you do not click on any group, all species will be included.

Some species thrive in a broader spectrum of pH, in which case they are included in several of the groups, e.g. both in neutral and alkaline (or acidic), some may thrive in all water (in terms of pH) and are then included in all three groups.

This heading describes where the species originates from. Sometimes the same species is found in several continents, then it is of course included in all continents where it occurs. Worth mentioning is also the continent "Oceania" where we also count Australia. This is not entirely correct, but we have done so for practical reasons. If you click on one of the continents, only species that come from that continent will be included. If you do not click on any continent, all species will be included.

Red listing is a classification of different species (animals and plants) where an assessment is made of resp. species 'risk of extinction'. The purpose of the classification is to find out which species are threatened and on this basis investigate which measures need to be taken to improve the situation of an endangered species. This red list is coordinated by the International Union for Conservation of Nature (IUCN)

The international code systems in which the different species are categorized are these

EX (Extinct)
EW (Extinct in the wild)
RE (Regionally extinct)
CR (Critically endangered)
EN (Endangered)
VU (Vulnerable)
NT (Near threatened)
LC (Least concern)
DD (Data deficiency) = Lack of knowledge (so far there is not enough knowledge about the species to be able to make a reliable assessment).
NE (Not evaluated)

In all Zoopet's species descriptions, this classification has been included and further information on the main reasons for different species becoming extinct, as well as how to act as an aquarist if you keep species that are classified as endangered.