The cycling procedure is something that has to be done when you initially set up your marine fish tank for the first time.
Because of the relatively high levels of ammonia and nitrites in the tank during this procedure, you will only be able to introduce one or two fish that are suitable for salt water aquariums that are robust, such as damsels. Since these compounds are toxic to fish and invertebrates, you shouldn’t add too many specimens to the tank until there is sufficient bacteria to convert these compounds into nitrates, which are not harmful to the tank’s livestock. Until then, you shouldn’t increase the number of specimens in the tank.
I could go into more detail about this and provide it for you to read here, or you could watch this video instead, which not only explains the technique but also includes some fantastic footage of a stunning marine fish tank. Absolutely, I’d sit down and watch that video!