Fishes can die if you clean the aquarium with heavy chemicals or because of your lack negligence. You can clean it without using the chemicals. It is advised to clean the tank once a month if you start doing it this way.
How to clean aquarium – First Steps
Make sure that all cables are plugged out (pump and lighting). Take a bowl and take everything out so that it doesn’t drip. The majority is easy to wash except the glass. Gently catch the fishes using a net and place them in a plastic bag filled with aquarium water and then transfer them along with the water into another clean bowl. This way, it will be less shock for the fishes. Move them, for now, to a quieter part of the room.
Aquarium cleaning preparations
Take out the most of the water from the aquarium (with a plastic cup or pour it into a bowl). If it’s possible move the aquarium to the balcony, yard or bathroom tiles (but make sure to put an old towel or a rug underneath it). Prepare a sponge with an abrasive or a nanosponge which don’t require the use of a detergent. Take out all the decoration from the aquarium and put it in the bowl. Rinse them first. Take the pump apart and clean it well, especially the sponge inside the pump. If you have rocks in the tank take them out, wash them and leave them aside. It is recommended to keep only a few rocks behind which the fishes can hide in the tank because of easier maintenance.
You clean the aquarium with water and a sponge. If the calculus can’t be removed, try some rough sea salt (but make sure to wash the tank properly). You can also clean the aquarium by not taking everything out.
Changing the Water
The new water shouldn’t be too cold or too hot and you can pour it using a hose or a bucket. If you use the chlorinated water from the public water supply, you should let it sit for 24 hours).
Never buy fishes if you don’t buy cleaner fishes. Usually, two or three fishes require one cleaner fish (Plecostomus and Otocinclus). Also, there are special cleaner snails which live in aquariums. However, they can be a problem because they eat plants and breed very quickly, so stick to regular cleaners