Hello all,
I have 5, now 4, Rainbowfish (Melanotaenia praecox) in a 29 gallon tank with 3 blue-tail tetra, a bull shark, a pleco, a betta, and a dwarf gourami. I have a hanging power filter (with bio), heater, and all the usual treatments. My water is very hard and the pH is >8. I have had...