Lemon Tetra with red sores
I just picked up 10 lemon tetra. I acclimated them etc. One had a reddish sore on his side. The red (light red) sore appeared to be raised. I put them in the tank around 10:00pm and my midnight it had died. I wake up to find the next morning one more has died. I returned them and got two more last night. One of the new ones has a similar sore on his head (raised and red). This morning a different one was dead. The one with the sore on his head is alive but the sore seems to be getting worse. He seems to be slightly gasping (the first one that died was gasping near the bottom as soon as i but him in the tank).
There does not appear to be spots on any of the fish.
Also in the tank (55gal) are
4 assorted angels (nickle sized i picked up last week)
1 black molly
1 silver molly
(the mollies i picked up same time as the angels.
All the other fish appear to be fine
What is this, and how do i treat it. Should i stay away from copper based meds?