New Tank Syndrome




Welcome to the wonderful hobby of aquarium fishkeeping! When starting a new aquarium, you have to introduce your new fish slowly into the aquarium. We know you can’t wait to have your tank full of fish, but you have to allow nature and its biological processes to develop properly for the health and safety of the inhabitants.
One of the most important aspects of a successful aquarium is the nitrogen cycle and its ability to act as a biological filtration. This filter conditioning process takes between five to seven weeks to develop in new aquarium setups. This initial period is referred to as “New Tank Syndrome.”
A key factor in enjoying this relaxing and rewarding hobby is understanding that your aquarium is much like a mini ecosystem. In order for your fish and plants to thrive in the beginning, patience and attention to detail will aid in lessening toxins in your aquarium and speed up this biological cycle.
Selecting Your First Fish
Your first fish selection is very important in establishing your new aquarium. They are needed to consume food and produce waste to start the biological cycle. They have to be able to withstand the temporary high levels of ammonia and nitrite, which occur during New Tank Syndrome. A Petland pet counsellor can assist you in selecting the most suitable fish for your aquarium. The initial type and quantity of fish will depend on the size of your aquarium and the overall species your are planning to have. Some fish species are too sensitive to these conditions and do not react favourably to New Tank Syndrome.
What Happens During New Tank Syndrome
First, you should set up your aquarium and let it run for 24-48 hours (to allow debris to settle and ensure your aquarium heater is maintaining the correct water temperature). Now you can introduce your first fish. Follow the recommended landing procedures as instructed by your pet counsellor. Your fish can be fed one to three times daily by using small quantities of food as outlined in our Do Your Fish Look Hungry? Petland tip sheet.
In the first week as the fish secrete their waste, it will accumulate as ammonia in the aquarium. A colony of beneficial bacteria (Nitrosomonas), in the water, will begin to “feed” off the ammonia and convert it to nitrite. In some aquariums the bacteria may not develop successfully in the first couple of days. This bacteria bloom will present itself as cloudy water but shouldn’t be a cause for concern and will clear up within a few days.
Ammonia in the Aquarium
If the ammonia rises too high (above 10 mg/L), it may pose a deadly threat to the fish and the Nitrosomonas colony. To reduce the ammonia, we recommend placing ammonia removing zeolite in your aquarium filter especially during the starting period of your new aquarium. It is also beneficial to perform a 20% water exchange using an aquarium gravel cleaner.
The Nitrosomonas usually takes approximately seven days to establish a sufficient colony for your aquarium. This process can take longer in cold water or marine aquariums, or if the fish were not fed properly. We recommend daily ammonia water testing to accurately observe this stage of New Tank Syndrome.
Nitrite in the Aquarium
Nitrite is not as harmful to most fish as ammonia, but over a prolonged period can dangerously compromise their oxygen-absorbing capabilities. After seven days a second beneficial bacteria (Nitrobacter) will colonize within the aquarium filter media. These bacteria “feed” on nitrite and create the common plant fertilizer ingredient nitrate.
This second bacteria takes quite a bit longer to multiply and establish in the aquarium. The average time is from four to six weeks. In the first two months of your aquariums’ operation, we recommend using an aquarium bacteria supplement on a weekly basis to assist in the development of both beneficial bacteria. The development period of Nitrobacter differs from one aquarium to the next depending on the aquarium size, specific water conditions and fish feeding procedures.
If the nitrite rises too high (above 25 mg/L), it can dramatically prolong the development of the Nitrobacter colony. We recommend performing a 20% water exchange once a week (during this period) using an aquarium gravel cleaner to dilute the nitrite level. Aquarium filters can be rinsed in de-chlorinated water, but should not be replaced during this cycling period.
When the Nitrite Aquarium Water Test returns to 0 mg/L, it is safe to add more fish to your aquarium. Introduce only a few fish at a time on a weekly basis until you have reached a safe capacity for your aquarium.
Nitrate in the Aquarium
Nitrates, unless found in high levels, are usually not harmful to the fish. It will, however, increase the growth rate of algae and aquarium plants. The most common methods of reducing nitrates, is to perform a 20-25% water exchange using an aquarium gravel cleaner every three to four weeks to dilute the nitrate level. We recommend growing live aquarium plants whenever possible. It is a natural method of reducing the nitrate in your aquarium and slowing down the growth of algae.

no2 and no3 levels in aquarium

Alleviating Stress in the Aquarium
The stress created from elevated ammonia and nitrite can have some ill effects on your fish. Testing your aquarium’s water quality is the best method to identifying these stressors. Having your own aquarium test kits at home is beneficial and convenient. Ask a pet counsellor which are best suited for your aquarium. We also offer free water testing for hobbyists who sign up for a Club Pet Membership.