High nitrites in new fish tank, and my fish won't eat. What's wrong?

You mention that your water tests all zeros. Which parameters are you referring to ammonia and nitrite? If so, have you measured your nitrate level? Though not as toxic as ammonia or nitrite, nitrate is still harmful to fish especially in concentrated levels. Please test your nitrate levels and if your levels are higher that 40 ppm, perform a series of small water changes (10%) every other day to slowly lower your nitrate level to under 40 ppm.

Thanks for reaching out about Goldie. There are two concerns here: (1) not apparently eating and (2) high ammonia. For the appetite, try to note if there is feces. If feces, then eating. If appear getting thinner, then not eating enough. For the second problem, this is probably new tank syndrome, and not allowing the biological filter to establish. Water changes are needed to bring down the ammonia as that is toxic to the fish and damaging to the gills. Probably the reason for the frantic swimming. Good luck.

There are a few possibilities including normal adjustment or something wrong with the water quality. Also, you will need a bigger tank for Nutty that includes a filtration system. Here is a link about goldfish care: https://www.petcoach.co/article/how-to-help-your-new-goldfish-thrive/ https://www.aqueon.com/information/care-sheets/goldfish Make sure the water quality is good for Nutty. I hope this helps and please feel free to post any additional questions.

It is possible the tank has not cycled properly which results in high ammonia and nitrite levels which can kill fish. Allow the tank to run, without fish, for at least 4-6 weeks. During this time, use a home test kit or submit a water sample for testing every few days. The local Petco may do this for free or for a small fee. What you are looking for is to have ammonia and nitrites at 0 ppm and nitrates at 20ppm or less. pH can hover around 7 for most community fish. Avoid large, rapid swings in pH though. What is happening in the tank during this time is that beneficial bacteria are populating the gravel/substrate and the filter. These bacterial populations are responsible for the Nitrogen Cycle. This cycle breaks down wastes from fish, uneaten food and plant matter into by-products that are filtered out or dissipate. You can "cycle" a tank with fish, however this increases the risk of loss. Once your tank has cycled, you can add fish. You will still need to monitor water chemistry and perform partial water changes regularly. Use only conditioned water that is temperature matched to prevent stress or shock. You will also need to vacuum the gravel regularly and rinse the filter media. Never use tap water to rinse. Use a bit of tank water to protect bacterial populations in the sponge.

Hi, You will need to test for ammonia, nitrite and nitrates now that there are fish in the new tank. If the biofilter is not well established in the new tank, then the abrupt presence of fish will cause an ammonia spike. You should do a partial water change, ensure proper aeration of the water. There are products you can get to boost the biofilter if this is in fact the issue. You should also consider the number of fish for the just meet of gallons in the tank as overcrowding may be a contributing factor. If you need further guidance, please don’t hesitate to request a consult. Good luck!

They may be stressed from the trip, the water may be too cold (low temps can affect appetite in fish) or the water chemistry may be off. Consider a partial water change. Use only conditioned water that is temperature matched to prevent further stress or shock. The fish food is fine. They will likely eat it once conditions are corrected and they settle down.

The most common problems if ammonia is persistently high is overfeeding, overpopulation and bad water quality. Did you try already to change the water completely, cycle the tank and what is the PH of the water? Lower pH below 7.0, full water change and reduce feeding are all essential steps. I would recommend to avoid the use of any chemical ammonia remover. Please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.