Hi at the weekend I got 6 Rummy Nose tetras and some lava plants to add to my collection. In the last 2 days 4 have died and so have 5 of my Neon Tetras (which I've had for over a year). All my water readings are fine. Went back to fish shop who said possible cause could be that because I have no air pump it could have starved the fish from oxygen. Anyway air pump now in place but any other steps I could take or should take to prevent any further losses. I'm feeling devastated. Any advice greatly appreciated.