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Common goldfish in fish ponds - Proper care

The common goldfish is easily the most recognisable fish that is available to purchase as a pet but sadly over recent years it is also one of the most misunderstood and in some cases a neglected species. It has the reputation of being very hardy, this statement does not mean that it has no special requirements, like all fish species they must still be given the correct conditions to thrive in and with a happy life, breeding often follows as a natural progression with these fish.

At one time it was considered fine to offer the goldfish as a prize at fairgrounds where they were stored in small plastic bags, these specimens often only survived for a couple of weeks when they were taken home, thankfully this practice has now been banned in many countries. Goldfish bowls are now being unfavoured as keepers realise that these fish need space and what better surroundings to house these fish than in a fish pond where they have the room to live and swim about how they should be without the restrictions that has in the past lead to stunted growth and short lives.

Knowledge about the common goldfish is essential if you are considering keeping these fish and where better to start than to go back to their origins when this species of fish first appeared as the result of selective breeding. Hopefully this article will enlighten you and make you realise just how wonderful these fish actually are!

Origins of the common Goldfish

The early origins of the goldfish are shrouded in a bit of a mystery, this is mainly due to the closed contact between China and the rest of the world but it is agreed that hundreds of years ago many species of carp were reared for food and that the common goldfish originated from one of these species. As the fish were being reared it was noticed that certain colour mutations were appearing, namely red, orange or yellow colour variations. After several generations of breeding in ornamental ponds a gold variety appeared and this proved to be more popular than the more common silver varieties so the breeding intensified until the deep gold colouration were embedded for all time.

It wasn't until the 1500's that fancy varieties of the goldfish appeared with longer flowing fins and some strange body shapes and these have still proved popular today albeit they are less hardy than the common goldfish itself.

In the 1600's goldfish appeared in Europe and from then on became popular all over the world until we reach present times and they are still the most widely recognised fish available to keep.

Types of Goldfish

Courtesy of: The Aquarium Guide

Caring for Goldfish in the aquarium or fish ponds

Goldfish require the correct environment to lead long and healthy lives, they are a very active species so require a lot of swimming space, high water parameters etc., always remember this and as mentioned at the start of this article, goldfish and goldfish bowls are not compatible with each other. Each specimen of goldfish will require at least 20 gallons of tank space initially and for each fish added afterwards you can add another 10 gallons of water volume. If your tank or fish pond is home to 6 goldfish then you will require at least 70 gallons of water volume. The aquarium or fish pond should be fully cycled i.e. the filter must house large enough colonies of beneficial bacteria to convert any ammonia or nitrites present in the water column into nitrates. The nitrates can only be removed by adding plants or partial water changes so that they remain at a safe constant level.

If using plants in your fish pond or aquarium expect the goldfish to have a few nibbles, they find them hard to resist but by using hardy, fast growing plants there will always be a good plant life where you keep the fish.

The fish pond will definitely need to be fully cycled before adding the goldfish and stocking levels now come into the equation!

All fish need space, if they are overcrowded disputes over territory can occur and the filters can become overloaded if the bacterial colonies cannot cope with the large amounts of fish waste and detritus decaying, not only can this lead to high toxic levels but also algal blooms will occur in the water column creating a green, murky appearance which is never pleasing to the eye.

It is a common mistake to work out stocking levels from the total water volume in the aquarium or fish pond, it is far better to work out the stocking levels from the actual surface area as this will determine how much oxygen can be absorbed into the water, providing a healthy environment for your fish. The general rule is 24 square inches of surface area for each inch of fish added, the length of the fish should be determined from their adult size, not the juvenile size. If your fish pond has a surface area of 1440 inches then it is possible to keep 60 inches of fish in there, this normally relates to 10 fish of 6 inches in length, less if the fish are larger and more if the fish are smaller.

The filtration system must be rated for the size of your fish pond or aquarium, aim to turn over the full water volume every hour at least, twice the water volume per hour is a better ratio. The end product of the filtration process is nitrates in the water, plants will consume the nitrates but partial water changes will also need to be performed to keep the nitrates in check.

Regular cleaning of the pond or aquarium is also a must, particularly the substrate of bottom of the fish pond, gravel cleaners can be used in aquariums, fish pond vacuums are ideal for fish ponds.

The filters themselves will require cleaning on a regular maintenance schedule or they can clog and become efficient, remember that any sponges in the filters must be rinsed in aged pond or aquarium water, never rinse them under fresh mains water or this will kill off the bacterial colonies.

Feeding your Goldfish

Feeding the goldfish is quite straightforward as long a s a varied diet is provided that meets the dietary needs of the fish. They are a very greedy species so overfeeding can be a problem, restrict the amount of food that is offered to a feed that the fish can totally consume in a five minute period.

Any excess food left over will simply decay and foul the water in your fish pond or aquarium. Unfortunately the common goldfish can be prone to problems with it's swim bladder, this is often caused by feeding constantly with dried foods, soaking the food prior to feeding should prevent this.

A good balanced diet will consist of quality flake or small pellets (pre-soaked), this can then be varied with some vegetable matter such as blanched spinach, blanched peas, or even spirulina. For meaty foods, live or frozen foods can be offered, blood worms are definitely relished by the common goldfish, take care though, overfeeding with live or frozen foods can lead to digestive problems.

Blanching is a simple process, al that is required is to add the vegetable matter to boiling water for one minute, another method is to place the vegetables into a microwave for a few seconds, the end result will be the same.

Smaller feeds 2-3 times per day are far more beneficial than one large feed per day but do not feed your pond fish in the winter months and slow down the food prior to winter as the metabolism of the goldfish will slow down.

Breeding the common goldfish

If given the correct conditions, the common goldfish will spawn on a regular basis, outside in the fish pond this will occur in the spring months as the water temperature increases, in the aquarium a constant water temperature all year round should mean that its possible to breed the common goldfish whenever you wish to set up the breeding project. In a fish pond a group of goldfish are normally added dependant on the water volume that the fish pond can hold. Adding a group can ensure that you actually get goldfish from both sexes, in the aquarium a group can still be added as juveniles and allow them to grow on, separating a male and female when you are ready to set up the breeding, more importantly when the fish are ready to spawn!

Sexing the goldfish can be a bit tricky when you first attempt this but there are several tell tale signs that will allow you to determine whether you have male or female specimens.

As the fish mature males tend to develop a slimmer body shape compared to the females, this is more obvious as the females belly starts to swell with eggs. The males will also develop white pimples on the gill plates and pectoral fins as spawning time approaches, their fins may feel thicker than the females as well.

You can also vent the fish, this method is commonly used, especially by breeders and invlolves turning the fish over and checking the vent near the anal fin. The female's vent will be more prominent than the males and this method is a very accurate way of sexing your fish.

Preparing the fish for breeding can take a few months, especially for pond fish as spawning follows the winter period when the fish are on shut down, as the water temperature increases, the fish will be ready to spawn in the spring months. The parent fish will need to be conditioned with protein foods after fasting in the winter, dried foods should be avoided, adding a heater to raise the water temperature by a couple of degrees will also help with the spawning process. Look for tell tale signs on the fish such as the abdomen of the female swelling with eggs and the white pimples appearing on the gill plates of the male. Spawning mops should be added to the shallowest part of the fish pond and the parent fish will start to chase each other around the fish pond. Eventually the fish will go into the spawning mops, this usually takes place in the morning and the eggs will be laid and fertilised, the whole process can take a few hours so allow them time to release all of the eggs and allow the males to fertilise them before moving the spawning mops to a suitable vat or a similar container.

Raising the fry

The eggs should take about 4 days to hatch, do not expect a 100% success rate, some eggs may not be fertilised and some may develop signs of fungus. Any eggs that turn white will not produce fry and can be removed. When the fry first hatch they will consume their yolk sacs so do not attempt to feed them until they are free swimmers, initially they just latch onto anything they can and are known as “wrigglers”.

Once free swimming the fry can be fed on a commercial egg layer fry food or Infusoria (green water), newly hatched brine shrimp are also ideal. After a week, the spawning mops can be removed and the fry allowed to grow on. Any deformed fry can be culled so that quality offspring are raised and once large enough they can be added back to the fish pond or sold off to other fish keepers.


To summarize, the common goldfish have needs the same as any other fish and should be given the correct conditions to be housed in, this will ensure that you have healthy stock that wil give you pleasure for years!

If you decide to keep fancy goldfish it is best not to house these with the common goldfish, they cannot compete for food and are not as hardy as the common goldfish!

Happy fish keeping!