Vet Q & AMy Tetra fish keep dying. What's causing this despite my best care?
I am so sorry that you are having this problem! With multiple die offs of fish, one of the first things to consider is that the water quality may need to be addressed. I didn’t see you mention in your post whether you have been able to assess that or not, but it would definitely be something to evaluate. Things like high ammonia, high nitrites, and high nitrates can be devestating for fish. Also, if your filters are not working properly, or are not in the correct set up, that can also contribute to fish death.
From the clarity of your water and the lack of substrate and tank furniture, it makes me more suspicious of this contributing to your issues.
The other major reason for multiple fish deaths are infectious diseases (bacteria, parasites, fungus) - but ideally these would be diagnosed by a veterinarian. There are many over-the-counter medication treatments at pet stores for these, however they can be damaging to your water system, so ideally would not be used unless you know the problem that is going on.
Updated on September 24th, 2025
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