Fish Tanks & Aquariums
Transparent tanks with a lid in three sizes, small tanks with LED lighting, a desktop model with a USB pump and a heated tank for bettas in one place. The multiplied dimensions give the volume of the tank and not the volume of the water, so go by litres and not by centimetres. The bacteria live in the filter and take four to six weeks to multiply, so until then no fish belongs in the tank. The betta needs heated and filtered water and a tank from about fifteen litres up, so these tanks suit plants, decoration or shrimp rather than a fish.
Fish Tanks & Aquariums
A small desktop tank fits on a desk and on a shelf, but the water behaves in it differently than in a large one. This category contains transparent rectangular tanks with a lid from 24 × 18 × 13.8 to 34.5 × 25.5 × 19.5 centimetres, small tanks with LED lighting, a desktop model with a built-in USB pump and a tank for bettas with LED light and heating. The tanks are made of non-toxic plastic, which is easy to clean but scratches sooner than glass, though a scratch can be polished out of it. Before buying it is worth checking whether a heater and a filter of the right size are available for the tank, because without them the use stays limited.
The litres on the label and the litres of water are not the same thing. The multiplied dimensions give the volume of the tank and not the volume of the water, and the desktop model of 21 × 11 × 19 centimetres does have over four litres, yet it holds only 1.8, because it is not filled to the rim and part of the space goes to substrate and equipment. The difference shows most in the smallest tanks, because there every decilitre is a large part of the whole. Oxygen gets into the water through the surface and not through the volume, and a tall narrow tank supports fewer inhabitants than a wide low one of the same volume.
Water does not stay in balance by itself, the volume, the filter and the bacteria keep it there. The less water there is, the faster the temperature and the amount of ammonia change, which is why a small tank is more demanding to look after than a large one and not easier. A tank without a heater follows the room temperature, so at night and when the room is aired the temperature drops. The lid reduces evaporation and stops the fish from jumping out.
A new tank is not finished at the moment it has been filled. The bacteria that turn ammonia into nitrite and nitrite into nitrate settle mainly in the filter and take four to six weeks to multiply, so until then no fish belongs in the tank. The start can also be made without fish, by dosing ammonia or with a little food, and it is finished once the test shows neither ammonia nor nitrite. Without that comes the so-called new tank syndrome, in which the fish dies of its own waste.
The betta is a tropical fish and is still sold to live in cold bowls. It needs heated and filtered water and a tank from about fifteen litres up, so it does not belong permanently in any tank in this category. The smaller tanks suit plants, decoration or shrimp, which however tolerate ammonia worse than fish and therefore have to wait for a matured tank just the same.