After having the fry for nearly a year now, I decided to add a new Chagoi which was of similar size and had been quarantined. After one week of adding the fish I realized that some of the fry began to flash. Thinking that it was just cold I added a heater and brought the temperature up to around 17c.
With continuing problems I went to the local store and got a scrap done. I was told early stage of costia. Being told this I treated with malachite and formalin. After a week nothing had changed and I began to loose fish. I took some fish to another dealer to get another scrap because i wasn't satisfied. This time i was told that the fish was clear, however it was a bacterial issue. I then used achriflavin. Another week down the line and i am still loosing fish(40 of the 94). However i realized with the ones that were dead they lacked fins and a tail and the skin and scales were beginning to rot (I will include a photo for reference). All water parameters are fine. Just want to know what others think and how i should go about it from here.