I have setup a new fish tank. Its a 55 gallon and I let it run for 1 week. I started to add fish 4 oscars, 2 plecos, a green terror and three catfish. They all started to get signs of ich. Most of them have died. For the last week I have been using ich treatment and nothing seems to be working. Could this be ammonia poisoning? Should I remove all the fish and start over? Please let me know what I should be doing.