Best Fish Tank Stocking Guide For Different Fishes

The optimal volume of water in the aquarium is necessary for the natural life of aquarium fish. In order to find out how many fish can be kept in an aquarium and where to find fish tank stocking guide. Here it is necessary to take into account both the size of the fish, as well as their aggressiveness and the amount of waste produced. Let’s try to figure out which of the formulas offered on the network are most correct.

best fish tank stocking guide for different fishes

Conditions of fish tank stocking

Aquarium fish, like all life on earth, need oxygen. Since we are talking about limited space, the lack of water, and, consequently, the oxygen contained in it, can adversely affect the health of the fish.

Another factor to consider is living space. In overcrowded reservoirs, even non-aggressive fish can have conflict situations. Fish with bitten tails and fins will not decorate your aquarium.

Also important is the size of adults, their food activity. Larger fish excrete more waste products, resulting in an increase in the level of toxic nitrogen-containing products – nitrates, nitrites, ammonia in the aquarium.

Signs that may indicate overpopulation:

  • fish swim to the surface and gasp for air or stay in thickets of plants;
  • the inhabitants of the aquarium have a paler color;
  • poor increase in growth, fish grown in cramped aquariums rarely reach the size characteristic of this species;
  • lack of offspring.

The situation with overpopulation can be partially solved by additional means – blowing water and powerful filters, frequent water changes and a slight decrease in its temperature – within the normal range for these types of fish, of course. Planting live plants will help saturate the water with oxygen, it is important not to overdo it here – it will be difficult for fish to move in dense plantings, and it will be difficult to see them.

By observing all these conditions, it is possible to solve problems with overpopulation or increase the population density. But it should be remembered that an aquarium packed to capacity is unlikely to serve as an aesthetic spectacle.

Basic techniques for fish tank stocking

There are many formulas based on a comparison of the total length of the fish and the volume of the aquarium. Example: “For 1 cm of fish, 1-2 liters of water are needed.” Such calculations can be immediately discarded as untenable.

More true can be considered those of them that are compiled taking into account the physiological and characteristic features of individuals. Such formulas are based not only on the length of the fish, but also on their completeness, the amount of excreted waste, aggressiveness and the need to live in a flock. Equally important is the ratio of the size of the aquarium to the size of the fish, as well as its surface area. It is known that the higher this indicator, the better oxygen is absorbed from the air.

Calculations can also be made on the surface area measurement. For example, for small fish with a narrow oblong body, 90 cm² of surface is enough, and for large and “chubby” fish – at least 150 cm². Formulas for measuring the area of ​​a rectangle, square or circle (for those who have forgotten the school curriculum) can always be found on the net.

Large and schooling fish large aquariums, small. Perhaps such a statement will sound like a common truth, but just imagine how you will look for small guppies in a 100 liter aquarium, or how a 25 cm Astronotus will feel in a 50 liter aquarium.

fish tank stocking As Per Litre for fishes

fish tank stocking as per litre for fishes

So, it’s time to talk about specific fish and their volume needs.

  • small fish up to 4 cm long (cardinal, neon, endler guppy, parsing). Such “crumbs” are kept in small aquariums, from 10 to 30 liters, and here the rule works with might and main: for 1 liter – 1 centimeter or even one fish;
  • small fish up to 6 cm long (guppies, barbs, pecilia, blackthorns, rhodostomus, minor, hasemania). “Pool” is needed more – from 20 liters, the optimal population density is 2.5 liters per fish, this parameter can be reduced in aquariums with a large volume;
  • small fish up to 10 cm long, which are peaceful in nature (mollies, congo, swordtail, black and cross barbs). These inhabitants of aquariums are mainly characterized by flocking behavior, therefore, experienced aquarists advise choosing a place of residence for them, taking into account a large number of inhabitants – at least 150 liters, at the rate of 3 to 10 liters per fish. Moreover, the smaller the aquarium, the more water is needed per individual;
  • peaceful fish about 20 cm in size (goldfish and its breeding forms, danio malabar, gourami, iris). Such fish need larger aquariums – from 200 liters, and the larger their volume, the greater the density allowed. For example, no more than 2 scalars and 3-4 goldfish can be planted in a 100-liter aquarium, while 50-60 individuals can get along freely in a 500-liter one;
  • large fish, up to 30 cm in size (cichlazoma, discus, acara, astronotus). Aquarium – from 250 liters. With a minimum volume, you can keep from 2 to 5 fish maximum, that is, at the rate of 50 liters per one. With an increase in volume, the density can be increased, for example, in a 500-liter one, up to a dozen individuals will fit;
  • very large fish (flower horn, Indian knife, snakehead, aravan, clari catfish). Such specimens need a more spacious “apartment” – preferably at least 500 liters per couple.

fish tank stocking Based on Fishes

There are fish to which it is impossible to apply the general concept of population density.

fish tank stocking based on fishes

cichlids fish tank stocking

The diversity of their species and behavior does not allow us to talk about a single population density. These are fish that are jealous of their own territory. It is believed that a little overcrowding can slightly mitigate their aggressive nature.

Small cichlids, up to 10 cm long (seyjik, black stripe, sun), need aquariums of at least 40-60 liters per couple. The aquarium increases – the population density increases. For example, already in 150 liters it can “live” up to a dozen black-striped cichlases.

Medium-sized cichlids, up to 30 cm (small Tangani and Malawian) need a larger aquarium – from 150 liters. As mentioned earlier, light overpopulation is allowed – the volume is calculated from 10 liters per individual. The arrangement of the bottom will also help to solve the problem with aggressiveness they just need places to hide ( grottoes , snags, large bushy plants).

Bottom fish, suckers, and burrowers fish tank stocking

The number of catfish and bots, as a rule, is not taken into account in the total number of inhabitants of the aquarium, but their size should not be overlooked. For example, for 1 ancistrus you need an aquarium of 50 liters, for 1 plecostomus – already 250.

labyrinth fish tank stocking

An exception to the general rules are labyrinth fish – they are practically indifferent to the oxygen content in the water. For example, a lone cockerel will feel fine almost in a glass of water, and a couple of gourami in a 20-liter aquarium.

fish tank stocking For Fishes live in groups or flocks

It has been noticed that peaceful fish living in flocks are much calmer, which means they consume less oxygen than loners. Such species are shown to be kept not even in pairs, but in small “companies” in this case, and their population density can be safely increased.

fish tank stocking Based on living layer of fish

The aquarium should be populated on all “floors”. If you don’t know what breed the fish belongs to (bottom, inhabitant of the middle or upper layers), look at its “muzzle”. The turn of the mouth of the fish to the bottom will indicate its addiction to “digging” in the ground, it prefers to live in depth. The mouth of the fish is directed straight – its place is in the middle layers, up – on the surface of the aquarium.

Tips for Safe Stocking of Aquariums

When calculating the ratio of fish and water, it is imperative to reduce the volume of the aquarium by the amount of soil (it is approximately 1/6 of the total volume), and by the volume that remained unfilled with water. Also note that young specimens are acquired more often, which increase in size with age. Calculations are made taking into account the “adult” size of the fish.

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