So I have a 29 gallon planted tank. It WAS populated with 6 guppies, 1 platy, 4 amano shrimp, 4 ottos, 3 albino cories, 1 African dwarf frog, 6 neon tetras and 4 baby neon tetras. My tank has been running for about 2 years and my second last addition was the 6 neon tetras about 6 months ago. However, last week I added 2 more ottos, 2 guppies and 6 amano shrimp. Since bringing them into my tank my fish have been dying one by one in the last 7 days. The losses include 5 neon tetras (one of them appeared to have fungus), 2 ottos, and 1 guppy. Also, my platy seems to have fungus growing on her tail. All of my remaining fish besides the platy look normal but so did the fish that died before they died. I tested my water and everything is in the normal range so my question is how do i treat the platy? I do have an extra 10 gallon tank but i feel like i should just treat all of my fish because there is definitely something going on. I have the API fungus cure and I'm worried about my plants (I have jungle vals and anubias), my shrimp, my baby neons, the ADF. I need advice on what is the best way to approach this. Thank you!