I moved my clownfish and cardinal fish to this 10 gallon quarantine from a 3.5 gallon last night. Waste was building up in the small tank and ammonia was too high so it had to be done. I woke up this morning and my Cardinal was dead. I have no idea why he died plus my clownfish is fine. I acclimated the fish properly and tested the qt tank water levels before I put them in. The only thing I can think of that killed him might have been me. I was adding seachem prime to the tank after I put them in and the Cardinal swam right up to the big cloud of prime and started breathing it all in. Maybe it messed him up? He started acting kinda strange after but I thought he was just freaked out because of the new tank. Please let me know if you have any idea as to why he died? I want to avoid making mistakes like this in the future.
You could be right about the Prime. Next time try mixing the Prime with some saltwater from the tank and then dumping it in. Some of us do this with meds as we add them to the tank too. Especially meds that don't mix very easily like General Cure.

