I am new to this board and I hope someone could spare a little knowledge on how I could possibly fix my problem. I have lost 3 fish in the 5 months. My water readings are all withing acceptable range. I have my tank for over 6 years now and I have never encoutered this problem before. I purchased a Valentiny puffer about 5 months ago. I slowly introduced into my tank by placing him in a container that would float on the top of my tank so the fish store water would slowly become at the same temperature as my tank. I would add about 10 ml of water ever hour until I was at a full 2 cups of water. I then placed him into a net and put him into my tank without dumping teh water he was just in into my tank. I fed them teh next day, a frozen marine mix and everyone was happy to eat. The following day everything was fine. The following morning to that day was a different story, the puffer was now dead without any traces of injuries nor any disease, He still had all of his color as well which meant it wasn't a long time that he had passed away. I have a 50 Gallon tank with a protein skimmer, a bio wheel and two powerheads that feeld the units just mentioned. I have an Eheim canister filter as well. I have 1 yellow tang, 2 damsels and 1 clown. Once I found the dead puffer I did my regular 5 Gallon watter change, and kept the same gravity of 1.021 and the temperature remains at 77 degrees Fahrenheit. A few days later a damsel died but he died during the middle of the day and he his eyes where already eaten. I was very stunned that a damsel would die. I test the water and everything was ok. The Nitrites and Nitrates where a little higher then usual but nothing my fish stores or my fish friends said would cause the problem. I then quickly change another 5 gallons to reduce the nitritas and nitrates. I proceeded to do my weekly 5 gallon water change and just recenly I introduced a Procupine puffer. Not two days later my oldest fish of 1.5 years passed away, he seemed to have a white cyst growing on his stomach but this may have been there for his entire life and I never noticed it. Now my porcupine puffer only ate on the two first feedings that i have given him. He has not eaten in almost 1.5 weeks. He simply puts the food in his mouth and spits it out. The yellow tang and damsel are still fine and eating. I am really woried that something is killing my fish 1 by 1 and I don't see any symptoms besides the fish not eating then just dying. Please help.
Thank you
Thank you
It's already wife approved. 