Many of us eat, hear about or see baby fish without ever considering their true adult size. A lot of fish that may seem small and manageable can grow up to be colossal fish that defy our expectations.
In this list, we have 10 such fish that are a mix of aquarium and sea creatures. Hopefully, there are a few surprises for you along the way.
Goldfish
Goldfish are possibly the most misunderstood fish. They don’t have bad memories, shouldn’t be kept in small tanks, and can grow some unique facial features. As with many fish, a part of these misconceptions can be due to how a small living space can stunt their growth.
If you asked people to estimate the size of an adult goldfish, they’d perhaps guess a few inches. In reality, when in ideal conditions, these beautiful creatures can grow up to 16 inches, with the largest record goldfish being 19 inches long.
This can lead to pet owners discarding goldfish into lakes and ponds as they grow too big for their tanks. Goldfish can be one of the more demanding fish to own and people need to think twice before buying them.
Tuna
Tuna is one of the most commonly eaten fish in the world and it would be easy to think they were a medium-sized fish. In reality, they can be incredibly huge with Atlantic Bluefin Tine able to reach a length of up to 10 feet and 1,000 pounds in weight.
They are fast and powerful swimmers, and not the type of fish you can catch using a simple fishing rod. Due to their vast size, it means they can contain a vast quantity of meat, making them extremely expensive. The most expensive tuna ever bought went for an eye-watering $3.1 million.
Manta Ray
Many people may have spotted rays in an aquarium or in the ocean, and presume that all rays are a similar size. However, manta rays can be majestically large and have a wingspan of up to an astonishing 29 feet.
With that size can come a weight of up to 3,000 pounds. Despite that size, they gracefully glide through the water and can be seen off the coastlines of tropical oceans. If you ever get the opportunity to dive with manta rays, expect to lay your eyes on a beast of the seas.
Sturgeon
The sturgeon fish is most known as being the creature responsible for giving us caviar. These freshwater species are extremely old, with estimates suggesting they have been roaming around Earth’s waters for more than 2,000 years.
Some species can grow up to 24 feet and weigh over 3,000 pounds. These fish can dominate rivers and seas across the world. They are one of the few creatures that were around in prehistoric times, but can still be misunderstood.
Catfish
Catfish is quite a vague term as this species of fish can range from small to ginormous. When found in ponds and lakes, they can grow massively. The Mekong giant catfish can grow to 9 feet long, and some North American varieties grow to six feet.
Pleco’s are a type of catfish that are commonly kept in aquariums and are usually much smaller. However, they are similar to goldfish as they can grow much larger than expected. As always, double-check you can handle their full adult size before buying any fish.
Knifefish
Here we have a similar story. The knifefish is often seen as a great fish for aquariums due to its small size and unique features. One of the most loved varieties is the Black Ghost Knifefish which can grow to nearly 3 feet in the wild.
As with goldfish, their growth will be stunted if they are not kept in ideal conditions. Despite their name, these are harmless creatures which use a weak electronic signal to navigate their way around the world.
Marlin
For anyone who follows baseball, you’re probably already aware that marlins are found off the coast of Florida, with the Miami team being named after them. What you may not be aware of is their sheer size, as these unique creatures can grow up to 16 feet long.
With their spear-like bill and incredible speed, they are one of the most impressive hunters in the ocean. The Black Marlin holds the record of being the fastest animal in the water, being able to reach an incredible speed of over 80 miles per hour.
Cod
Cod is a much-loved fish in many countries, such as the US and the UK. However, they are far from your average fish. The iconic Atlantic cod can reach sizes of up to 6 feet and weigh over 200 pounds.
They love living in the deep, cold waters of the Atlantic Ocean but have faced many challenges of overfishing. Their popularity even led to the “Cod Wars” which was a series of non-military disputes between the British Isles and Iceland.
Salmon
Salmon is another fish commonly used for its meat. There is a misconception about them being relatively small. This is in part due to salmon farms where they are raised in a controlled environment and harvested when they are still quite young.
Wild salmon can be much bigger, being able to reach over 5 feet in length and weigh more than 100 pounds. With their incredible migrations and ability to jump out of the water, they are an amazing species that can present an incredible challenge to anglers.
Arowana
We end with another species that can be an aquarium nightmare. People may buy a cute little arowana before realizing what it can grow into. They are beautiful fish which in the right conditions can grow to be over 3 feet long.
You need both a large and long aquarium to give an arowana a happy life. They grow quickly and are also known in the wild for their speed and agility. 150 gallons is the minimum tank size needed for arowana, as otherwise, they may need to be rehomed.
