I am writing this article to tell you something about aquariums in general. However, not about those big aquariums which can be found in Zoo's or museums, but about home fish tanks. Of course, if you have a castle, or really big house, your home aquarium can be as big as those public ones. On the other hand not everybody is Bill Gates, or Queen of the United Kingdom. For us, ordinary people, smaller versions are produced.

But from another point of view, small doesn't immediately mean it's small too much; It's relative. Even in a small flat or house you can have aquarium with capacity of few hundred litres. Basically, you can have only 10 litres aquarium as well. Bear in mind that introducing any fish into such small tank would be crime. Small sized aquariums are more suitable for plants only.

Previous idea leads me to the first point: tanks division based upon living beings. You can have, as I just wrote, a plant of a fish tank. And you can have an aquarium, which contains fish and plants living together in peace and harmony. Especially the harmony aspect is very important. Some fish prefer green food, and we can say that healthy looking aquarium plants are irresistible for them, but some fish need plants for hiding purposes as well. If such species don't have enough hiding places, they feel stressed and they can even die. On the other hand we know species which don't require plants necessarily, but they love to lay on their leafs and they also appreciate smooth touches how leafs slide through their bodies when swimming around.

Now, when you know that there is a direct relation between fish and plants, you should know something about various fish species compatibility. Let's take a quick look into the natural food chain; It's not the rule every time, but almost every time that larger fish eat smaller ones. Naturally, there exist exceptions where some little aggressive fish can eat the a big one as well. Piranhas, Puffer species, etc., etc. And this is how it goes in home aquariums too. An aquarium with many peaceful fish is called community aquarium. An aquarium where you keep aggressive fish and small peaceful fish together can be called a dinner time. And the last type is characterised by many aggressive fish kept in one little tank; This is called “fight to the dead” or “fight until the end”. Generally, I recommend community tanks instead of second and third case.

Previous paragraph shows you that it's important to know everything about fish you want to own. Focus on temperament primarily. If you are beginner, there are some species, you should start with. These species are not demanding, and they don't require much care. I am talking about Guppies, Platies, Mollies, Swordtails, Neon tetras, etc. These species are very peaceful and harmless, sometimes shy. Bear in mind that they should be kept in shoals, what means you shouldn't keep 1 or 2 of them in one tank, otherwise they will not feel happy. Plecos and many catfish species belong to this “not demanding” group. Unlike fish which do best in shoals, they don't need to be kept with too many specimens of their family or genus. Plecos require driftwood which becomes their most favourite place as time goes by. They suck it all day long. Another good fish for beginners is betta fish. Especially males are beautiful. They exist in many colour variants and their big fins look like jewels in the tank. They don't harass other species, but if you put two males into one aquarium, they will kill each other. Nobody knows why. Once scientist put two males into very big garden pond, but they found each other and started to fight immediately. So how they could survive the evolution? In Thailand where they live in lakes, there is an alpha male which is the boss and nobody is fighting when he's in.

If you aren't a beginner any more, you can try for example Gouramies – bit aggressive, territorial and they eat everything small, what is or isn't moving sometimes. Another nice species is the Angelfish. But they grow to big sizes, so they need a big tank. This category includes also Cichlids which come from America, Africa, and many species originating in Asia.

But if you don't mind to spend a lot of time and and if you have enough experiences, you can choose a demanding fish, like the Discus fish – it needs special water conditions, or puffer fish. Fish from this group need special water, special feeding, or they breed unusually. Or they even need large aquarium, like Oscar fish, freshwater Sharks, or Koi carps. Sometimes it is better to keep them in garden ponds and not in the tank in the room.