My garden pond is under a kentucky coffee tree. When we got home from vacation the entire water surface was covered with the flower pods. Unbeknownst to me, they are toxic to fish. 4 fish were dead so I took the remaining 4 and put the in the other pond. They have been responding well as of last night, today I checked and the girth on 1 goldfish is twice the width of the head. What happened?