Answer:
Goldfish are coldwater fish. As their water temperature rises in Spring to over 65F the fish come into breeding condition. Once they are ready the males nudge the females and chase them. During the chase the females scatter adhesive ova (eggs) amongst the plants at the surface of the water and the males scatter their milt (sperm) over the ova which fertilises them. After spawning has ceased, the adult fish should be removed because they will eat their eggs and their young if they can.