Why Fish Die After A Water Change And How To Prevent It

Regularly changing water in the aquarium is an important factor for maintaining a healthy environment in it. But for many beginners water change has proved to be a mishap.

- Shahu Sardar

Many complain about death of fishes after a water change, which would mean that water changes are bad for the tank. But this is just the result of some common mistakes made by the hobbyist.

THE ECOSYSTEM OF OUR TANKS

Fishes are not alone in the tank; with them are plants and some good bacteria, all three interacting with each other to create an ecosystem. The fish waste produced contains toxic ammonia that is broken down into simpler, less toxic components by bacteria and is further taken up by plants.

The formation of this ecosystem and other changes are very slow. Any changes in water chemistry occurring naturally take place very slowly and thus fish get acclimatized to it.

WHAT GOES WRONG?

It’s an irony that super clean water can kill your fish, than water that has bacteria and parasites in it. Large water changes that include more than 60% water change, rinsing gravel, cleaning filter media lead to a complete, massive change in the water chemistry. Fishes when put in these new conditions, lead to temperature shock, stress, loss of appetite, and then death.

As stated earlier, tank water contains useful bacteria that help in keeping water free from toxic ammonia present in the fish waste. Large water changes lead to the elimination of these bacteria. Those living under the gravel get washed off while rinsing it and colonies get destroyed when we clean the filter sponges/filter media. Fishes when produce fish waste containing ammonia remains in its toxic form due to the absence of these bacteria. The accumulation of ammonia leads to ammonia burns and then the death of the fish.