The most common beginner mistakes.
• Overeating: feed your fish, not the aquarium, otherwise the latter can easily turn from a clear crystal into something resembling biomass. Many fish reflexively display “hungry” behavior to beg generous owners for an extra portion that will only harm them. Uneaten food quickly poisons the water, and the natural toxin neutralization process does not have time to complete before the next overfeeding.
• Clean, transparent water does not at all mean that a seemingly prosperous aquarium does not need care and routine maintenance. The nitrate level in the water is not externally reflected until one fine day the aquarium turns into something resembling a small swamp.
• The passion for keeping an aquarium sometimes takes an insatiable character. Every month there are more and more inhabitants, but this is completely inconsistent with comfortable conditions for keeping fish. Ultimately, the inhabitants of a densely populated aquarium wither and even die. An aquarium is not made of rubber, and each individual inside it must account for a certain amount of volume in liters.
If the aquarium is still overcrowded, installing an additional filter and aerator can partly solve this problem. However, it is still better to catch “excess” fish that are not so valuable for this particular aquarium and give them to the nearest kindergarten. This action will relieve tension in the aquarium and allow its inhabitants to live in more comfortable conditions, which will certainly affect their well-being and appearance.
• When buying new fish, you should not immediately add them to an established community. Individuals from unfamiliar farms can be carriers of various parasites and pathogens. Such carelessness often causes the death of all aquarium inhabitants. Restoring the aquarium after an epidemic will require its complete disinfection, as well as all decorations inside it. It is much easier to keep fish in a quarantine aquarium for up to 2-3 weeks to detect signs of disease and disinfect them.
• Many species of fish in nature are food competitors, zealous defenders of their territory, or simply cold-blooded predators. Therefore, when choosing fish or introducing new inhabitants to the aquarium, their behavioral characteristics must be taken into account. You can consult pet store sales assistants about their temperament and compatibility with other fish species. If you act blindly, the chance of introducing a “wolf” for your “sheep” into the aquarium remains very high. A predator will swallow both cheap and expensive, elite fish with equal ease.
• Plants look spectacular in an aquarium, but far from all fish can peacefully coexist with them. Some prefer to feed on plants, others disrupt their root system, and others pull them up, thereby ensuring themselves a good view since they do not tolerate strangers on their territory. All this must be taken into account when choosing fish and plants. In addition, the latter need special lighting, fertilization, and care. Aquariums with a height of more than 55 cm are poorly suited for plants. Light propagates much worse in an aqueous medium than in air. Thus, the brightness of the initial lighting does not reach the bottom where plants live, which is not enough for their development and growth.
Care of decorations, cleaning of stones, ceramics, and glass in the aquarium.
New tank syndrome. Setting up an aquarium. 
