helo to everyone.... Ammonia is one of the the biggest killers of aquarium fish.It occurs in atank that is newly set up, however it can also occur in an established tank when too many fish have added at one time. Wen the filters fail due to power and mechanical failure or if bacteria colonies dies off due to sudden change in water. The worst factor in ammonia , it is a gas and it cannot be seen. Regular water testing and change elavates the amount of ammonia found ni the aquarium.It is essential to do regular water check ups to eliminate bacteria. In the cycled aquarium, nitrogen cycle simply put structure whreby fish masses, metabolism decomposing matter is converted to ammonia nitrates and nitrogen. Nitrogen is converted by plants, the nitrayes are removed and kept lowered by regular water change. Without this system water resistence, quality would change and huge amonts of ammonia are kept prsent all the time. Ammonia canges to ntrites if it weel prevented, but nitrites are also toxic and can the fish and damage its environment. The trearment of nitrites result in to nitrates:  nitrate is best suitable for the fish`s environment because it is not harmful to the fish ,plant and water. The cycly of nitrogen occurs automatically to benefit bacteria in terms of growth and produce to consume toxins produce by fish and dead leaves from the plant. The fish seem quite unsteady in dity water so i remove uneaten food sustances and floating particles. The water change is mainly for the reason to keep amont at low levels as possible to sustain the surronding of fish.