goldfish grow

How Big will My Goldfish Grow? How Big was the Biggest Goldfish?

Most of us have seen a goldfish placed in either a crowded tank or a small fishing bowl. We cannot deny it that when we see a goldfish in these areas, we usually think they are living happily and healthily. Plot twist? This is a false assumption.

When we place a goldfish inside a tank with proper size and accurate filtration system, believe it or not, a small goldfish can grow more than what you think. If you are asking how fast do goldfish grow and the things you can do to make your cute fish grow bigger, you are in the right place.

In this post, we are going to provide you with the important information you need to know about your aquatic pet growth. So, if you want to know more about it, let’s get started!

Table of Contents

    How Big Was the Biggest Goldfish Ever?

    A common misconception of people owning a goldfish is that they assume this aquatic creature grows only a few inches. Well, the goldfish you see in a bowl rarely grow well. This is because they don’t get the best nutrients. With the proper care, goldfish can grow bigger and larger.

    The biggest pet goldfish and the longest aquatic creature has a measurement of 18.7 inches long. Another is a 15-inches goldfish found in the United Kingdom.

    You can also grow your pet goldfish more than these sizes by keeping them in a pond or tank with a bigger size. The size of their environment affects their growth. The practice of keeping your goldfish inside a small tank does not make any good to your pet. So, make sure you are giving them their basic needs, including the right shelter size.

    How fast do Goldfish Grow?

    Goldfish develop around one inch each year, growing most rapidly throughout their initial couple of months of life. Unlike a lot of other typical pet dogs, goldies keep developing throughout their lives. Goldfish do not grow in streams, depending on their conditions as well as other factors. For instance, a goldfish that stays in an exterior pond will grow extra throughout the spring and also summer during the water is more heated, growing less during the wintertime season when the temperature drops.

    What’s the Reason Behind their Sizes?

    The genes of a goldfish are the primary reason behind their growth and size. Just like humans, fishes also have different genes. That’s why some variants of this aquatic creature have a higher chance to grow larger and longer compared to others.

    On the other hand, goldies given proper care become healthy and can grow up to a few inches longer than its average size. As mentioned, goldfish can grow at its best size when placed in an area with proper conditions. The proper conditions we are talking about include enough supply of healthy foods, warm water temperature, good-quality water, and an enormous tank or pond space.

    Water Problems

    Goldfish can tolerate various water problems, hard, soft, acid, or alkaline. However, they won’t endure water with ammonia or reduced oxygen levels triggered by air pollution.

    Constant water changes are required for Goldfish. This is specifically essential for fry when large numbers are often kept in congested conditions for the first few weeks.

    Another similarly essential factor for water modifications is Goldfish produce hormonal agents that hinder development.

    This is why there is the extensively held idea that Goldfish only expand to the size of their container.

    What occurs is the development of growth, preventing hormones from quitting the fish, and any other Goldfish in the same container, from expanding any bigger.

    Food Type And How Much Food Needed

    Goldfish have huge appetites. It has been asserted fry will certainly eat their body-weight of food a day if adequate is offered.

    I don’t doubt this claim assessing the amount of food my fry goes through in a day.

    Many hobbyists don’t give fry sufficient food to expand at their maximum price, which is critical for the first month.

    Fry needs to be fed live food for healthy protein. Some excellent quality ready foods can be supplemented at around a week.

    Average Weight of a Goldfish

    A goldfish weighs approximately 8 ounces. The weight of a goldfish varies depending on different factors, including their age and variety. The fancy goldfish varieties look slimmer and longer than the ordinary ones. Since then, according to the experts, they have an average weight of approximately 12 ounces.

    Wild Goldfish – How Big They Can Get

    With the size, there is a vast difference between the goldfish taken care as a pet and the goldfish that grows in the wild. Wild goldfish can grow approximately 14 inches long weight 3 lbs. averagely.

    You might ask why? Well, the following is for some reasons.

    First is their environment. Goldfish in the wild receive a sufficient supply of oxygen. Aside from that, the wild also provides a sufficient amount of natural filtration and water. Goldfish need not be afraid of the natural predators. They have all the required conditions to grow healthily.

    How Big Can a Goldfish Get in a Tank?

    Well, the answer to that question depends on different factors. Goldfish captive in a small bowl or aquarium only grows about two inches long. Some people think two inches is the normal size of a goldfish. But this is not true. They grow even longer.

    According to studies, goldfish do not stop growing as long as they live. But it restricts their growth every time we place them in an area that does not suit their natural needs. The reasons behind it are as follows;

    First, a small bowl or tank cannot provide the aquatic creature with it enough oxygen. Second, one of the natural characteristics of a goldfish is being messy. When they are messy inside their tank, it can contaminate the water in no time. When the tank does not have the proper filtration system, the water accumulates nitrates and ammonia, which causes the fish to get ill.

    All the mentioned reasons pose risks to the health of a goldfish. Their tank gets messy and dirty, and they receive an insufficient supply of oxygen. These two restrict not only the fish to grow healthy but also lead them to death.  

    Whether you believe it, if you have a pet goldfish and want to grow it at its full potential, give them the proper care; enough oxygen and proper filtration system.

    How to Make Goldfish Grow Faster

    As mentioned, proper care is the most important factor to keep in mind when growing a goldfish. There are lots of misconceptions about growing a goldie. But with the right knowledge and proper care, they can grow at their best.

    The following are some ways you can do to grow your goldfish faster. Note them.

    Tank Size

    Most varieties of goldfish can grow with gigantic size. But the problem is that their owners place them in a small tank. If you don’t have a large tank for your goldfish, we recommend you not to pet it. This is because a small-sized environment can restrict its growth.


    Just like humans, to grow well, we need to consume nutritious foods. To grow your pet goldfish healthy, feed them with foods rich in protein, including baby brine shrimp and micro-worms.


    Another important factor to consider when growing a goldfish is the temperature. Goldfish want to stay in an environment with a warm temperature as they can receive enough amount of oxygen and boost their activity level. It’s ideal to place your goldie in a tank with mid-20 degrees Celsius temperature.

    Water Quality

    Aside from being an important factor in the health of your fish, excellent water quality also affects the fish’s growth. So, change their water weekly.

    Final Thoughts

    If you want your aquatic pet to reach its optimal growth, the best thing to do is ensure that all the necessary requirements and proper care are given.

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