Have had my tank up and running for some time and no new fish for months. System was running smooth until I got a whole house water filtration system. Goes through a sediment filter and a carbon filter, then an alternative water softener. There is no salt use in the softener. Did a water change and noticed a massive die off in tetra, about 15 in a few days. I am losing up to 5 a week now. My Danio, Barbs, Pleco, Mollies, Snails, and Goldfish all seem to be completely normal with no loss.
Are tetra that sensitive that they would die off so rapidly? Did I strip too much out of the water and need mineral replacement? At a loss figuring this one out.