I have had tropical fish all of my life. I recently had a 55 gallon with a large ornate bichir, two large blood parrots and another common bichir. We moved and I lost all but the ornate and one blood parrot in the move. I lost the other parrot a month ago and I was left with the Bichir. He did fine in the tank. I had tried putting a few other things in the tank with him like some african cichlids, another blood parrot, and I would always wake up to find the other fish dead. I figured he was killing them overnight. I decided to get rid of the remaining bichir and my kids wanted some fun tropical fish. I got some guppies, and they all died within hours. I tested the water and my nitrates are high, around 80 ppm and my alkalinity and ph tested high also (ph tested toward acid). I am at a loss. I dont know whether to start over and drain the tank and start fresh or just treat the tank. What should I do?