What You’ll Need
Spare tank (5 US gals or more)
Brine shrimp cultivating kit
Aquarium salt
Methylene blue
Sponge filter and pump
Ice cream tub
Silk or real plants
Sexing Fish
The male goldfish will look more streamlined than the female, who will have a rather round looking belly. Also, the females vent (anus) will stick out whereas the males will not (although, as I have found, this method is not 100% correct but about 1% of the time, you’ll find a male with some identity issues!). Around breeding time, the males will get a line of spots on the first bone of the pectoral fin and gill covers like this:
Making Goldies Spawn
This is one of the most challenging parts of breeding goldfish. Some of the most successful ways to trigger spawning is to lower the temperature of your tank to about 64-68f for about 1-2 weeks. The tank needs to have real or silk plants in so the female has something soft to get bashed into to lay her eggs in. During this cold period, feed your fish lots of high protein meals (tubifex etc) and feed often. This will mean you have to do more regular water changes due to more waste being produced which will help with spawning induction. By this time, the female should look very round with eggs and fat. Then gradually warm the tank up to about 75-78ºf over the space of a few days.
During Spawning
While your fish are spawning, as the males follow the female constantly with their head up her backside she may get a bit battered, especially if your female is breed that tends to waddle like a pearlscale and your male is something like a common or shubunkin. If she gets too beaten up, take her out. If you're new to breeding, take out the plants with the eggs on and put them in a spare tank and wait for them to hatch. If you are very familiar with breeding and handling you fish, I would recommend hand spawning. Take the male(s) doing the chasing and put them into an ice cream tub or something like that filled with tank water. Gently squeeze the abdomen down to the vent. You should be able to see milt coming out. If it is a very fertile male, the water will be quite cloudy after a hand spawning session. Release the male back into the tank and take the female. Often, you just holding the female and her wriggling makes the eggs come out, if not, use the same method as you did for the male, only more gentle and as soon as the eggs come out, swirl them around with her tail to separate them as if they stick together, they will not develop properly. PLEASE DO NOT HAND SPAWN IF YOU ARE UNSURE OF YOUR ABILITIES OR ATTEMPT TO HAND SPAWN ANY FISH AT ANY TIME OTHER THAN DURING OR SHORTLY AFTER NATURAL SPAWNING. Squeezing a female while she is still very full of eggs can rupture the ovaries and cause potentially fatal internal damage. This is why it is best to hand spawn shortly after she has released most of her eggs during the natural spawning.
Care of Eggs
Once you have your tub of eggs, sink it in another tank of cycled water about (not stolen from another tank as this increases the chances of pathogens being spread onto the fry). The tank should only be 6” deep at this point and should be bare bottom. It should also have a sponge filter installed. Do not wipe off the algae from the inside of the tank as this is a good natural food for the fry. Put the temperature up to about 78ºf for optimal growth (if the tank is less than 5 US gals, don’t bother with a heater, it’ll just cook your eggs. Place in a warm room instead). I have found that adding aquarium salt to the fry tank at 0.3% concentration avoids problems such as flukes and should always be present with the fry at this concentration until the 4 month stage where they should be weaned off the salt gradually. Methylene blue is also useful for preventing fungus on small fry and eggs. Add some to the tank until the water is a ‘Windex’ blue. After a few days, you should be able to see little black dots inside the egg. At about day 5, the fry will move around inside the eggs occasionally. This should be around the time that they hatch. This is also the time to start cultivating baby brine shrimp. Kits can be easily obtained at you local pet store and aren’t too expensive or tricky to get going. I find other foods don’t kick start the growth of the fry and aren’t worth the bother.
Caring for the Fry
For the first couple of days after they hatch, the fry will hang off the plants of side of the tank. Do not feed them at this stage as they are re-absorbing their egg sacks. When they are free swimming, begin feeding small amounts of baby brine shrimp. Put in as many as the fry will eat in about 1-2 hours, four times per day. The fry will begin to look like fish in about 1-2 weeks. Do not do any water changes until the fry are about a month old and only do so very carefully with an air-line tube from the pump. However, you may need to get rid of excess food or dead fry from the bottom of the tank so a turkey baster can be a handy tool. At this stage, add soaked, crushed pellets to the diet. If there are any fry that are particularly small or particularly big, they should be separated from the rest of the group. At two months the fry should be getting big quickly so wean them off the baby brine shrimp as it can get costly when the fry are so big that they merely inhale the creatures! At three months, the fry should be changing colour and be about 1.5” big. For the next couple of months feed regularly, change the water regularly and look for homes for your babies!
If you do have any problems breeding, of course feel free to ask
as long as you dont say the "m" word 
even if they looked soo crowded in there 40 gal, swimming in nee deep algy, breathing in 3 week old poop of there parents 
will they die? i feel so stupid
). they hatched 3-4 days later, and now they have been hatched for a day and a half. they laid at the bottom and wiggled so i guess they were eating their yolk sacks.... they were then swimming around but i just checked on them and i cant see any swimming around (i only had about 5 that i could see alive because it was only a small batch of eggs) and they are laying on the bottom and not wiggling anymore... are they dead? i fed them a tiny bit of egg yolk just incase there was no food in the water, but it hasnt helped....