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Is It Essential To Have A Filter On A Tropical Fish Tank

Natural water filtration by rocks and substrate in a river

When considering filters on a fish tank we need to think about the overall picture of what we’re trying to achieve and to what level and aren’t able to generalise when answering whether you need a filter on a tropical fish tank.

A fish tank filter is designed to rid the aquarium of unwanted waste product produced by the fish living in it. It does this by breaking down harmful chemicals given off by waste products by them being eaten by beneficial bacteria which grows inside the filter. This keeps the levels of nitrate, nitrite and ammonia stable. This is a similar process to that which happens in the real world by rivers and streams etc running through rocks and substrate. This is why we need to have a filter on our fish tank, in order to ensure the water isn’t stagnant and gathering harmful waste.

Natural water filtration by rocks and substrate in a river
Natural water filtration by rocks and substrate in a river

There are different levels required though. For example, if you have a heavily stocked rift valley tank with plenty of Malawi cichlids for example then the waste produced per fish, per volume of water for that fish, will be very high. Therefore a large amount of filtration and large regular water changes are essential. On the flip side, if you were to keep one tetra in a 1000 litre aquarium then you wouldn’t need a filter and may only have to change a small amount of water infrequently.

I would therefore say that although it may not always be essential, fish keeping as a hobby is also keeping a pet and is our duty as fish keepers to provide the best possible environment for the animals we have chosen to take care of so would strongly advise always running some filtration when keeping tropical fish.