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How Big Do Goldfish Get

Goldfish are one of the low-maintenance and suitable fish for beginners with their peaceful behavior, gorgeous looking and great implied meaning. When we start feeding a goldfish in a fish tank, we should choose a proper tank for it, which is mainly determined by its size. But how big do goldfish get? Well, goldfish vary in type, which means their weight and length will be different. The average length is about 6 inches while the weight is 3-10 ounces.

In this article, we are not going to specify how big different types of goldfish get but focus on the average value.


How big do goldfish get?

  • In the wild: goldfish will reach 12-14 inches in length and about 5 pounds in weight.
  • In captivity: goldfish are much smaller in a fish tank since the room is limited. The full length is about 6 inches and the weight is only 3-10 ounces.


The largest domesticated goldfish in the world

The largest domesticated goldfish in the world is about 18.7 inches. Compared to other goldfish in captivity, it is a giant! And the weight is about 3 pounds.


When will goldfish reach their full length?

The newly born goldfish will grow very fast at the beginning. They will quickly grow to about 2 inches and then the growth rate will slow down, which is one inch per year.


How to help them reach the full length?

Better care makes better fish. To help your goldfish reach the full length, you should know how to take care of them to keep them happy and healthy. Followings are things you should do to better keep your goldfish.


Preparing a suitable tank

The size of a tank will influence the growth rate of your fish. If the space is limited, they will grow slowly and stop growing before reaching their full length. Also, a small fish tank will overstock easily and affect the overall environment. With a tank of 30 gallons, you can provide a single goldfish with enough living space.


Buying necessary equipment

  1. Goldfish produce much waste, which will contaminate the water quality, and water quality is essential to fish-keeping. So you need to equip a powerful filter in your fish tank.
  2. Goldfish do need a heater although they are hardy fish. The heater is used to maintain the water temperature since any changes will stress them.
  3. Aquarium light is needed to offer about 12 hours of light to your goldfish and to meet the light need of plants in the tank.
  4. To make goldfish happy, you can put some decorations in your fish tank, including some plants, rocks, driftwood and substrate. They can serve as decorations, hiding spots as well as toys for your goldfish.

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Feeding them properly

The word “properly” here means you need to not only feed them in the right way but also feed them with the right food. Goldfish are bottom feeders, you need to make sure the food can sink to the bottom of your fish tank, or you are wasting them while starving your goldfish. To avoid overfeeding, which is a detrimental problem in fish-keeping, you should remove the uneaten food after 2 minutes and feed them 2-3 times per day.

Goldfish are omnivores that will be glad about the following food:

  • Flakes
  • Pellets
  • Freeze-dried foods
  • Live foods
  • Vegetables
  • Tofu


Maintaining good water quality

In addition to using a filter, you should also clean your tank regularly. The frequency should be once per week. The most important part of tank cleaning is water change. You should change 30% of the water in your fish tank every week, but it is not a fixed number, you should determine how much water should you change according to the real situation. If you want to know how to clean fish tanks and change tank water, you can read other blogs on our website, which are more detailed and easier to understand.

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Keeping fish needs patience and perseverance. If you can pay more attention to them, they will in return bring happiness to you. With good care, fish can live longer and reach their full length, goldfish, for example, can reach about 19 inches in captivity! So when you start your trip in fish-keeping, get well prepared and take it seriously.

By the way, it’s possible that your fish stop growing although everything is fine. If this happens, don’t worry, they are born to be small because of their genes.

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