How New Aquarium Owners Usually Kill their First Fish
The most common mistake new aquarium owners make is to put fish into a new aquarium within the first couple of days after it has been set up. This often leads to the death of all or some of the fish as the tank has no way to get rid of the toxic ammonia based waste products that the fish will produce. While there are short-term ways to keep fish alive in an uncycled aquarium, the best course of action is to help the aquarium develop its own biological nitrogen cycle before adding any fish.
The most important thing to know about any aquarium is the nitrogen cycle. This continuous series of chemical reactions in your aquarium governs when it is safe to add fish, how many fish you can add, how much food to put in the aquarium, what kind of filters you need, and how often to change the water. If you get any of these wrong, you risk all of your fish dying from the accumulated poisons that will build up in the aquarium.
When you first set up your fresh water aquarium, with clean fresh water and a good filter sized appropriately for the tank, there is virtually no microbial activity in the tank. In a healthy aquarium, there will be a thriving population of microbes that are constantly working to break down the toxins released by the decomposition of organic matter or in the waste products of the fish themselves. The most harmful of these is ammonia. When establishing an aquarium, you should buy a good test kit that will let you check levels of ammonia, nitrates, and nitrites. By watching the levels of these chemicals in your water, you can determine whether your tank has an operating nitrogen cycle and whether you can safely add fish to your aquarium.
In the old days of aquarium keeping, the nitrogen cycle would be started simply by adding fish. Ammonia would build up in the tank and would provide a food source for the microbes that would convert the ammonia to nitrites. Nitrites are less harmful to fish than ammonia, but still toxic. Once a level of nitrites was built up in the tank, a new type of microbe would establish a population and begin converting the nitrites to nitrates. Nitrates are much less harmful to fish, but still need to be removed from the tank through periodic partial water changes.
It would generally take about 4 weeks, give or take a couple, for the proper levels of microbes to establish themselves in an aquarium. In the meantime, the toxins would reach very high levels and often kill the fish that had been placed in the aquarium, especially if there were several fish added before the tank had completely cycled. The second set of fish added to the tank would do better since the nitrogen cycle had been established by sacrificing the first batch of fish. Now, we know there are better and more humane ways to establish the nitrogen cycle in an aquarium.
Lack of basic knowledge about the nitrogen cycle and how to properly control the levels of harmful toxins in the aquarium is one of the most common reasons for new aquarium owners to give up and abandon the hobby altogether. Read the other articles on this website for complete information on how to establish and maintain a working nitrogen cycle in your aquarium without killing your first batch of fish. Future articles will also address preventing and curing common aquarium fish diseases, choosing the right fish for your aquarium, and many more helpful topics for both new and experienced aquarium owners.
