Hi, my tank is very well established, going on nearly a year and a half, however about 2 months 2 of my 6 guppies started showing signs of having tail rot. I used a treatment and that seemed to work, and their tails began to grow back. Since then my partner brought some Cherry Shrimp for my tank, and all was fine until the other day when I noticed that 1 of my other guppies is showing signs of tail rot. It's tail looks very opaque, and is jagged, it just puzzles me as to why he has tail rot. According to my testing kit, all my water levels are well within optimal range for keeping guppies happy and healthy, and I have good circulation and filtration. The problem I have is that now I cant use the treatment I did before as it contains copper which will harm my cherry shrimp. Can anyone offer any suggestions on how to treat it without harming my shrimp, and also any explanation as to why the tail rot keeps occurring? Thanks