Fish Lifespan: How Long Do Fish Live?

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As one of the oldest inhabitants of the planet, fish have been around for a long time. Fish are found in both fresh and salt water and are among the most abundant species on Earth. It's hard to find an aquatic habitat that doesn't house these vertebrates!

As such an interesting ancient species, it makes sense that we would be curious about their longevity. In this article, we look at the average lifespan of fish and how long they live in the wild and in captivity. Let's discover what makes this species so interesting!

Quick Overview of Fish Types

red animal siamese fighting fish
The earliest vertebrates on Earth were fish.


Fish have been around for 530 million years. They existed long before dinosaurs appeared on earth. They are classified as aquatic vertebrates with common external anatomy such as gills, fins, scales and mouth. The word fish applies to a wide variety of aquatic animals, including sharks, stingrays, puffer fish, eels, seahorses, and clownfish.

There are currently over 30,000 different species of fish. However, the total number of fish species is still not fully understood. We may discover another 10,000 species in the next few years!

How long can fish live?

colorful fish swimming
More than 30,000 species of fish have been discovered.


Fish lifespan varies by species. On average, fish live between one and 200 years, depending on the size and species of fish. Whether they live in the wild or in captivity also plays a role.

For example, the average lifespan of most wild freshwater fish is between 1 and 10 years. Fantail guppies, rainbow fish, axe fish, corydoras catfish and tiger barbs can live 1-3 years. The average lifespan of Betas and Jack Dempsey fish is between 3-5 years. At the same time, the average lifespan of angelfish can reach 10 years.

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On the other hand, wild saltwater fish can live for many years. Marine fish have a life expectancy of between one year and a century. However, you'll find some anomalies, such as the Koi Hanako, who is said to live to be 226 years old, and the Greenland shark, which is said to live to be 392 years old.

In general, the life expectancy of saltwater fish kept as pets is about 20 years. Pet freshwater fish generally live to be around 15 years old. According to a study conducted by the University of Michigan Museum of Zoology, pet goldfish can live up to 25 years under ideal conditions.

Fish Life Cycle Explained

The life cycle of fish varies from species to species. In general, however, fish go through the following stages during their life cycle:


The fertilized eggs hatch into fish. During this stage of development, the eggs will begin to develop organs such as eyes and tails. Sadly, even under the most ideal conditions, most eggs do not survive to hatch. This is because eggs face many threats, including changes in water temperature and oxygen levels, predators and disease.


When the eggs hatch, they are called larvae. The yolk sac is present in the new larvae. They get their nourishment from the yolk sac. Larvae can survive for 2-4 days on the food supply of the yolk sac. Once their eyes and lips are formed, they can be fed.


Baby koi, about 1 month old, in a fish tank.
Fry are usually 5-10 weeks old and can swim.

© phasaluka/

Once the yolk sac is completely dissolved, the juvenile fish are called fry. At this point, they are ready to start feeding themselves. Fish go through many growth stages. During the first few months, they are called fry.

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Once the fry undergo metamorphosis, the larval stage is over. At this stage, fish develop adult-like characteristics such as fins, color, body composition, etc., and they are classified as juveniles.


When a fish is able to reproduce, it is considered an adult fish. The time it takes for fish to mature varies by species and individual fish. Fish with a shorter lifespan mature faster. For example, female round gobies mature in about a year and live two to three years. In contrast, lake sturgeon can live 80-150 years, but females do not reach maturity until around 25 years old.

What is the most common cause of fish death?

As one of the oldest inhabitants of the planet, fish are very important to our ecosystem. This is why maintaining fish populations is necessary for all life on Earth. Several factors can kill fish living in the wild. These include sudden temperature changes, contamination or pollution of waters, disease and predators.

While fish in captivity don't have to worry about predators, they are susceptible to other problems. Fortunately, most pet fish deaths are easily preventable. Problems such as overfeeding, buying the wrong tank, and over-watering can all kill your pet fish.

How to Extend the Life of Your Pet Fish

Goldfish swimming in the aquarium
Goldfish are one of the most common pet fish.


Fish have grown in popularity over the years as a low-maintenance and generally affordable pet. Pet fish require proper care like any other pet. A fish may seem like all it needs is a tank and food, but there's more to extending a fish's lifespan.

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Let's review all the ways to best care for your pet fish:

  • New Tank Syndrome: A new tank doesn't start with the proper chemicals to create a healthy environment for your pet fish. This means that a lot of nitrates and ammonium can build up in the water. To avoid this, regularly test new tanks for nitrate and ammonium levels, and replace the water as needed.
  • Overfeeding: Fish eat differently than we do. Overfeeding fish can cause rotting food to contaminate the tank, which in turn can damage the tank chemistry. To avoid this, create a feeding schedule and stick to it. Wait until the fish has eaten all the food within 1-2 minutes, then stop.
  • Temperature Changes: While most fish can adapt to a wide range of temperatures in the tank, sudden or extreme temperature changes can create a stressful environment. This can make the fish susceptible to disease. Check the tank heater regularly and keep it away from heating or cooling vents.


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Rare Fish - Peppermint Angelfish
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about the author


Volia Nikaci is a freelance writer and content editor with a passion and expertise in content creation, branding and marketing. She has a background in broadcast journalism and political science from CUNY Brooklyn College. When not writing, she enjoys traveling, visiting used bookstores, and hanging out with her significant other.

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