Ok so heres the facts. I had a 4fter with 5 smal-med angels in my room, but was moving rooms. I set up a 2nd hand (tall 2ft) tank i got last weekend for them. I put the smallest in with a new 150 watt heater to test the water (so to speak) for 24 hrs before i added the others. There was some java fern and java moss in the tank with them, and i moved ofer my small internal filter from my 4fter (which had kept the water good for the 3 months i had had them for) This morning there were 3 dead, and the smallest that i added 24hrs before the others is still alive. Why do you think they died?