The question is, of course, interesting for a beginner aquarist. There are many data on the Internet, often incorrect, explaining how many fish you can run into an aquarium, starting from the displacement / volume of the aquarium itself. Beginners, after reading such data, run the fish and are unaware of how overloaded their aquarium is.
It seems to be done and aeration, and the filter in the aquarium is, but the fish still get sick and die. And they change the water, and pour the vitamins, but the fish still die.
Simply, initially, a mistake was made, which was in the wrong selection of fish.
Any aquarium fish prefers its own layer of water in which it lives. There are fish that swim in the middle of the water column in the aquarium, there are those that rush under the surface of the water. And there are those who just crawl along the bottom, for example, catfish.
If you start a lot of zebrafish in the aquarium, and pour the water over the surface with Riccia, then do not expect anything good. Danio rerio prefers to rush just below the surface of the water, and it is precisely her water layer that you have over condensed.
Run into the aquarium a handful of barbs, gourami, an angelfish and you will get an overcompressed middle layer of water. True, the barbs will clear their space for life by simply scoring and terrorizing the angelfish and gourami.
Scary, huh ?! Well, who said that creating an aquarium is easy?
How to choose the fish in the aquarium and how many of them should be.
As already written, fish prefer their own layers of water. How to determine in what layer of water does a fish live?
Very simple, look at her mouth. If the mouth is turned upwards, then this breed prefers the upper layer of water, below the surface.
If the mouth is directed along the midline of the body of the fish, then it is a fish of the middle layer. If it looks down, the bottom rock.
Accordingly, you need to pick up the fish in such a way that evenly populate all layers of water in the aquarium.
And here already, when determining the number of fish for each layer, you need to count on the displacement of the aquarium and the size of the fish itself. Yeah, the size also affects the number of fish in the aquarium, and you thought !?
And how many fish should be in the aquarium?
When calculating the number of aquarium fish that can be launched into an aquarium, beginners can use the simplest formula:
Fish up to 5 cm in length need 1 liter of water.
On a fish 6 cm long. 6 liters are required.
With large fish sizes, just plus a liter or two. Consider, this is data for aquarium with plants and aeration.
The truth is, there is one more thing that beginners simply do not know, the larger the aquarium, the less specific liters you need to fish. This is due to a larger surface area of water in contact with the air, that is, more oxygen will be in the aquarium.
But, I do not recommend making a communal flat from my aquarium, all beauty is simply lost, and the fish are constantly flickering.
For some aquarium fish, for example, an angel, it is important to have some kind of proper place. As a rule, the scalar couple takes a corner of the aquarium, and simply drives everyone away. This volume, which they occupied, you can safely delete from the total volume of the aquarium.
Similar, by the way, sin and gourami. Barbus same strive busy the whole aquarium.
When selecting fish and deciding the question how many of them should be, it is not necessary to populate the pugnacious, fast and slowly swimming fish in one layer of water. The same barbs, by virtue of their pugnacious nature, do not get along very well with slow scalaries, guppies and others.
The recently launched aquarium of 60 liters, I settled as follows: heels of medium-sized barbs, a few mollies, a couple of catfish at the bottom, and a handful, 10 pieces, leopard danios rerio. Skirmishes between the fish in my tank, after such a selection, are extremely rare. What you want.