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Let’s be honest, for generations, the lonely goldfish has always been seen as an inedible, ornamental fish species, having little functional value for day-to-day life. However, aquaponic gardeners are now realizing new potential for the fish to make big contributions to their plant ecosystems. The best part is that caring for goldfish in aquaponics systems can be relatively easy, allowing you more time to spend focusing attention on cultivating the perfect crop.
In this article, you will learn some tips on how to raise goldfish in an aquaponics setup.
Why Raise Goldfish in Aquaponics Systems?
Goldfish, which are relatives of carp and Koi, are among the popular choices of fish to use in aquaponics gardening. Readily available at most local pet shops and easily adaptable to various water conditions, Goldfish are a great choice for people looking to get started in aquaponics right away. Goldfish are masters at producing large amounts of waste, which translates to vital nutrients for your aquaponic plants.
While several species of goldfish can be suitable for aquaponics gardening, there are two distinct goldfish groups you need to keep in mind: single-tail (or slim-bodied) and twin-tailed (also double-tail or fancy).
The slim-bodied or single-tail goldfish are strong and fast. Most of the breeds in this group can grow up to 12 inches, which is why they’re a favorite variety to keep in ponds. If you go for this type, you can choose from common, comet, shubunkin, wakin, jikin, and watonai.
The fancy or twin-tailed goldfish, on the other hand, have egg-shaped bodies and are more preferred for ornamental aquariums because of their eye-catching appearance. Some of the breeds in this category include: fantail, ryukin, tamasaba, veiltail, butterfly, pompom, and telescope.
Requirements for Caring for Goldfish in Aquaponics Systems
Goldfish may be among the hardiest fish species for aquaponics gardening, but it is still important to pay attention to the details when creating a healthy environment for them. Below are some of the parameters to consider when caring for goldfish in aquaponics systems.
If you’re keeping fancy goldfish, the general rule of thumb is one fish for every 10-20 gallons. Single-tailed species, on the other hand, need more space, so you should have at least 40 gallons for one fish and 20 more gallons for each additional fish.
Goldfish need room to swim around, contrary to what you always see on TV where they’re put in a small bowl. That said, it is important to get a longer and bigger tank, especially since you’ll be keeping more than one fish. For example, if you want to keep five single-tailed goldfish for aquaponics, you need at least a 120-gallon tank.
Ideally, temperatures should be maintained between 65 deg F and 72 deg F.
Goldfish do not need direct sunlight, but they do benefit from having exposure to daylight. Keeping your goldfish tank in dark places can result in the fish turning into an unhealthy white color. The best approach would be to give your goldfish some light – but not too much of it – and provide shade.
Goldfish thrive at an ideal pH range of 7.2 to 7.6. While they can withstand pH variations, you should make an effort to maintain the ideal water pH.
A minimum dissolved oxygen concentration for your goldfish tank is 5 mg/L. Anything higher is ideal, while anything lower can put your fish under stress.
Best breeds for aquaponics
That said, you might want to go for this type if you are keeping your aquaponics system outside. In contrast, fancy goldfish will benefit more from indoor aquaponics setup, or an area with a mild climate and no significant temperature fluctuations.
Fish diet/nutrient requirements
Goldfish are omnivorous, providing a wider range of diet options. However, if you’re a beginner, it is recommended to stick to prepackaged fish feed, preferably pellets that are high in protein.
Goldfish have voracious appetites and will eat whatever food they can get, regardless if they’re hungry or not. For this reason, you should be careful about overfeeding and only feed as much as they can eat within two to three minutes, twice a day.
How to clean the tank
Goldfish are not invincible and can still be affected by illnesses. If kept in poor conditions, they become susceptible to bacterial infections, parasites, and fungal diseases. Be sure to address possible problems in your tank, such as overstocking or poor water quality, before attempting to treat any bacterial or fungal infections.
You can tell if your fish is sick if you observe, fraying or redness of tail, anal fins, and pectoral fins. Red open sores may also show, which indicates ulcer disease. If you spot a sick fish, put it in a quarantine tank for two to four weeks.
For a guide on common goldfish diseases and how to treat them, check out this guide.
Aquaponics plants best suited for
When to rotate fish in and out of the tank
Only add new goldfish to your tank if it has the required space. Keep in mind not to overstock as this could quickly result in poor water quality.
An external box filter is ideal to use since it doesn’t take up space in your fish tank. In addition, it is easy to maintain. But other than the type of filter, you also need to pay attention to the flow rate, which is the amount of water filter per hour.
If you want an efficient filter for your goldfish tank, aim for one with a minimum flow rate of five times the volume of your tank per hour. For example, a 20-gallon tank would best benefit from a filtration system that has a flow rate of 100 to 200 gallons per hour.
Can they be mixed with other breeds?
When caring for goldfish in aquaponics systems, keep in mind that twin-tailed and single-tailed breeds shouldn’t be put together in one tank. Single-tails tend to be faster and more aggressive than their twin-tailed counterparts, and thus might eat all the food before the twin-tails can get their chance.
You can, however, put goldfish and other fish types in one tank without problems. Many aquaponic gardeners have mixed goldfish with Koi and carp without any issues. It is also possible to put tilapia in your goldfish tank, but you need to make sure they are of the same size.
Remember to remove the male and female fish once fertilization is done because goldfish are known to eat their own eggs.