Keeping Fish Tanks Clean

For fish hobbyists keeping their pets’ environment clean is one of the most important aspects of animal husbandry. So here are some tips on how to keep your fishy friends clean, healthy and happy.


The first thing to do is to use an algae scraper or pad and give the glass a good clean on the inside. It is best to use a scrubber, scraper or pad that has been specially designed for cleaning aquariums as the similar-looking pads in hardware stores may have harmful soap or chemical residue embedded (potentially lethal to fish). Pet stores now stock a variety of algae scrapers and pads, including ones with long handles or even magnetic scrubbers. If the algae residue is particularly stubborn, scrape it off using a razor blade – make sure that it is a plastic razor blade if your aquarium is acrylic as otherwise it may become scratched.

Once you have done the glass, do the same with any rocks, artificial plants or decorations that have accumulated significant algae growth or are just very dirty. Remove them from the aquarium and scrub them with the algae scraper – if this does not remove all residue, soak them in a 10% bleach solution for about a quarter of an hour, then scrub again and rinse thoroughly in clean, running water. Allow them to air dry to remove any remaining traces of bleach.


While the rocks, decorations and plants are drying outside the tank, you can use this time to vacuum the gravel with a water siphon. Again, there are a variety of siphons available in pet stores but they all work in essentially the same way. When the gravel has been thoroughly vacuumed, turn your attention to the hood, tank top, light and outside glass. Do not use regular glass cleaners as the ammonia content is toxic to fish – instead, always use specially formulated aquarium cleaners and make sure that you rinse well. When this is done, you can return all the rocks and other decorations to the tank.


Do not clean the filter at the same time as the other parts of the tank. This is because the cleaning process will have removed or disturbed the colonies of beneficial bacteria residing in the tank, on the rocks, plants, decorations and gravel. These bacteria help to eliminate toxins in the aquarium environment and prevent a dangerous ammonia surge. Luckily, some beneficial bacteria will still be clinging to the filter media so by leaving the filter uncleaned, you will allow these bacteria to recolonise your aquarium and rebalance the ecosystem. So wait a few weeks after the main cleaning before attempting to clean your filter.

Change and replace any filter media that contain carbon, ion-exchange resins or ammonia absorbers, especially if they are more than three weeks old. However, if you have a “mechanical” filter such as ceramic rings, filter fibre or sponges, which do not absorb the toxins, then you can simply gently rinse them to remove any dirty and debris and then return them to the filter, instead of replacing them. Try to use water that is the same temperature as the aquarium water and return the filter media to the filter as soon as possible.

Finally, don’t forget to clean the filter tubing and other parts of the filter assembly. If you have dirt and sludge that builds up in the crevices, use a filter brush to help you remove them.


Perhaps as important as a periodic thorough clean is ongoing cleaning and maintenance – this will help to keep things under control and make things easier when you are doing a “major” clean. Thus, every time you change the water, think about giving the glass a scrape or the gravel a quick vacuum and clean any rocks or decorations as soon as you see any dirt or debris on them. The filter should be cleaned monthly, in any case and this is also a good time to soak your fishnets in disinfectant solution to help keep them clean and soft.

Remember that soap – even in small traces – can be lethal to fish so always designate a separate bucket for your aquarium use only to avoid introducing toxic chemicals into your tank.

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