There are many different kinds of goldfish and the size of them will vary depending on the type and the parents. Babies are usually 2mm at birth. A female goldfish can produce several thousands of babies at one time.
Baby goldfish are tiny - we are talking about 1 or 2 millimeters at the most. Goldfish are difficult to get to breed in most tanks unless the pH and temperature are exactly right. If so, you can get as many as 20 or 25 babies at a time.
