I'm pretty sure the softener is fish-safe, as it's hooked up to the whole house and my current fish don't seem to mind. In fact, a couple have been showing even brighter colors since it was installed.
Do you have any plant recommendations? Now that I look at the tank, the lighting is probably considered low.
My adventures in keeping Indostomus crocodilus, the crocodile toothpick fish. AKA armored stickleback, paradox fish, and freshwater pipefish. Care is (to the best of my knowledge) exactly the same as Indostomus paradoxus.