I've had healthy zebra danios develop curved spines, which is probably genetic.
Whats the tank size?
Tank stock?
Can you post as much of the water parameters as possible?
What test kit are you using?
Whats your setup like?
30 Gallon tank
right now I have:
4 GloFish
2 Zebra Danios
2 Cory Cats
3 Ottos
1 Snail that tagged along on a plant
5 Ghost shrimp
API Freshwater Master Test Kit (Ammonia, Nitrite, Nitrate, and PH), Is there any thing else I should/could be testing?
I've got a Marineland Penguin 200 filter
I'll get water parameters from my test kit in a bit.