How to successfully breed Goldfish in home fish tanks
Goldfish must be one of the most popular fish ever to be kept in the aquariums, they are quite hardy, easy to get hold off and very attractive when in full health. They originated from Asia, there direct descendants are the Carassius auratus species and were originally kept in terracotta pots in Ancient China. In their natural habitat the Carassius auratus inhabit lakes, streams, ditches or ponds and they can even survive in stagnant water. The goldfish was so popular in China that they appear in thousands of Chinese art pieces including pottery as well as traditional paintings. The fish that we see today has been bred through the generations selecting fish with certain dominant genes, this process allows for diversification and nowadays not only is the common goldfish available but there are fancy goldfish, single tailed and double tailed fish. These are not difficult fish to breed but preparing the fish for spawning needs to be done months in advance if breeding in the aquarium. I have kept lots of goldfish in my ponds and every year I left them to their own devices and always had lots of young without my help. This proves the point that surroundings can affect how we attempt to breed the fish. These fish are extremely difficult to sex when juveniles or less than one year old but after this when breeding season approaches the males will develop white pimples (tubercles) on their gill plates (operculum) and also on the leading edges of their pectoral fins. The females will deepen in body shape as their belly swells with eggs and their vent just in front of the anal fin will be larger than the males.
Preparing your goldfish for breeding:-
If this is your first attempt at breeding goldfish do not try to breed the fancy goldfish, get some experience with single tailed goldfish as these are less fussy about their water parameters and are hardier than the fancy goldfish. Whether you are breeding these in an aquarium or outside in a pond the general basics are the same but for this article we will concentrate on breeding goldfish in the aquarium.
Start planning your breeding program the year before you actually start the project and purchase quality stock at around August time, at this time of year there will be plenty of stock to choose from as many keepers will have surplus to their requirements and will be looking to sell them on.
Purchase a group of 6 goldfish that are about 6 months of age. This way you can more or less guarantee that you will end up with males and females but at this time you will not be able to sex them. Towards the end of the year the goldfish should be slowing down as external temperatures drop, reproducing this in the aquarium will give the goldfish a more natural lifestyle, at this time reducing their food intake will help to rid their digestive systems of excess food and give it the chance to clean itself out preventing any infections or associated diseases. This is a good time of year to add any precautionary medications as well, also clean and sterilise any breeding tanks that you are going to use. Keep the fish on a low intake of food until the next year and at march time you can start selecting your chosen fish for the breeding project.
Starting up the breeding tank:-
Use a three foot or four foot tank and give this another clean up before adding water, the water level should be set at 6” and it should be well aerated with an air stone. You will need to add a spawning medium for the future eggs, this can be plants, woollen spawning mops or even a plastic pan scourer that has been opened up and spread out slightly. The optimum water temperature for breeding is 20 deg C, if the tank is outside this can be reached with the use of an electric heater or if the tank is situated inside then room temperature should be about at this level anyway. Sex your fish at this stage, the females should now have a fuller body shape so they will stand out against the males. Select the best female and select two males, use the males that are very active and seem to be chasing the other fish, this is a good sign that they are getting ready to spawn. In the early evening add the two males and one female to the breeding tank and leave them undisturbed overnight.
Spawning may take place the next morning or a few days later, there is no fixed ruling on this but whenever it does start it will kick off early in the morning and carry on until halfway through the same day. The eggs will be scattered over whichever spawning medium that you chose to use and once spawning has finished the parent fish can be removed from the tank.
Hatching and raising the fry:-
After two days of being in the breeding tank the eggs should be clear in appearance but black dots should be visible, these are the eyes of the new fry. Any eggs that are white have not been fertilised or may contain fungus, if possible remove these but leave them if it means disturbing the healthy eggs. If the tank is kept at a constant temperature of 20 deg C the eggs will hatch after 4 days. The fry will be all over the tank and do not require feeding at this stage as they will still have a yolk sac attached which supplies them with all of the nourishment that they require. After another two days the yolk sac will have been consumed and the fry will be free swimming, now is the time to start feeding them. They will do best if supplied with newly hatched brine shrimp and the should accept this readily. It is best to feed them small amounts 3-4 times per day rather than give them one large meal a day as their stomachs are very small and soon fill up.
As always there will be a percentage of fry that do not survive, this is perfectly normal and does not reflect on your fish keeping skills, some may be deformed and will need to be culled but after a few weeks you should end up with a healthy batch of young goldfish.