Why are my new betta fish dying so fast after bringing them home?

Drop the water temperature to 80 F. Bettas do best between 78 F and 80 F. The higher temp likely did not cause her death, but warm water holds less oxygen than cooler water. She may have been ill or old. She does appear bloated in the image. It may have been dropsy or other infection. Monitor water chemistry using a liquid test kit. They are more accurate than the strips. Tou can also submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for 0 ppm ammonia and nitrites with nitrates at 20 ppm or less. Try to keep the pH as close to 7 as possible. Bettas can tolerate acidic water, but changes should be gradual to allow time for acclimation.

The most common cause of death of a newly acquired fish is usually shock or incorrect water quality. Fish tanks should be set up and left running without fish for at least 3-4 weeks to establish a proper nitrogen cycle. There are products that can shorten this time period. If this is not done, there may be high levels of ammonia, chloramine, nitrates and nitrites which can kill a fish. When introducing a fish, the bag should be floated in the tank for about 30 minutes to acclimate the fish to water temperature. This can prevent shock if the water is too hot or too cold. Test your water quality with a home test kit or submit a sample for testing. Most pet stores or aquarists will do this for free or for a nominal fee. Correct any imbalances as indicated. Slowly acclimate any new fish as written above. You can request a consultation to discuss your concerns in greater detail if necessary. Buying fish and starting a tank can be quite confusing initially.

I recommend to start with having the water tested. Many times this is offered by the pet store. If all the fish have passed away, the culprit is most often poor water quality, a disease or the tank not being properly maintained for the species of fish. I do not recommend to get more fish until you know the water conditions are correct and that you know the environment (temperature...etc) is appropriate for the species of fish you want to have. I hope this helps.

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.

I am sorry your goldfish passes away. IT is most likely nothing you did wrong. I would be concerned that the fish was sick before you every purchased it. Sometimes from local pet stores the fish are sick and the stress of transport can cause them to pass. I would contact the pet store and ask them if they have had any other fish pass away. I am so sorry for your loss

Thanks for using Petco Pet Education Center, formerly Petcoach! I am so sorry to hear about the passing of Norman. If the Betta tank is currently empty, I would suggest changing the gravel and cleaning it very well before putting another fish in it. Make sure to change the water regularly as this is often the cause of issues with Betta fish. Best of luck!

He is "old" for a Betta. Check the water chemistry and temperature. You can use a home test kit or submit a water sample for testing. The local Petco may do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with nitrates at 20ppm or less. Perform partial water changes to stabilize chemistry and/or to improve water quality. Use only conditioned water that is temperature matched to prevent stress or shock. Bettas do best between 78 F and 80 F. The cloudy eyes may be due to infection. Maintaining pristine water quality will help, but you may need a broad spectrum antibiotic as well. Look in the aquarium section of the local Petco for medication. Follow label directions carefully and remove the carbon filter insert during treatment if indicated. Even with treatment, there may be permanent damage to the eyes if the condition has been chronic. The "laying down" is sometimes seen even in healthy fish. They may choose to lay on gravel or the broad leaf of a plant. It may also indicate infection or injury though. If hebisbhavibg difficulty reaching the surface, decrease the water level to make it easier. Bettas need to surface occasionally to get some air.