Hey guys I recently purchased a young 20cmlong long cod it died yesterday very sad I kept him in a pond with six goldfish all where Perfectly fine except one which had cotton wool fungus on the side of him. all though there was a barrier between the cod and goldfish so I don't know what happened. the day before the cod died he gained the same fungal infection right before he rested with the fishes. But it was so quick I just don't know what happened. Pls explain the cod had already been sick once and we took it back to the fish shop. Where they looked after it for 4 weeks. we checked everything the ammonia level was zero and he was eating food I just don't know what happened