goldfish arent really pregnant. they have a bulge on one side of their body where their egg sac is. Once they are sexually mature they will always have this awkward bulge. I dont know exactly how long they have the eggs untill they release them but i know that the male goldfish will bump into the female goldfish at the start of the summer. Most breeders try to make them wait till May so that there wont be any cold periods that kill the fry. However, fish may start mating as early as march. once the eggs are released they attach to some plant and the male passes over it and releases its sperm. Actually the funny thing is any fish (not just male goldfish) can fertilize goldfish eggs. the eggs hatch very quickly in a matter of days because the parents do not protect them and may even eat them. the hatched fry will develop over the summer. It takes about two years for them to become sexually mature themselves.