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Fun Facts About Popular Freshwater Fish

Editing Team


10 March, 2023


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Freshwater fish are some of the most popular pets in the world because they’re quite convenient to take care of. They require little to no maintenance. They take up considerably less space. They are perfectly fine with little attention from you. They are easy and relatively inexpensive to feed, and they make calm and quiet companions.  If you are considering getting a fish for a pet, here are some fun facts about popular freshwater fish that might just help.


Photo by nonnatthapat

  • They are also known as the Siamese fighting fish. 
  • They can breathe air, thanks to a special structure called a labyrinth organ.
  • They are fiercely territorial which means they’ll most likely end up housing just one or (if you have enough aquariums), a few of them at a time, especially male ones.  
  • They can jump up to 3 inches above the water, so make sure your tank has enough clearance or a lid to ensure your bettas don’t escape.
  • They are carnivorous, so you’re going to have to feed them with insects, insect larvae, worms, or even small shrimps. 

Koi fish

Photo by Pexels

  • Like their distant but familiarly colorful cousin, the goldfish, koi fish have also descended from carps.
  • You can take care of them in an aquarium, but they are more suited to life in a pond. Jumbo koi, specifically, can reach lengths of up to 40 inches, so they will need a lot more space than what your regular aquariums can provide. 
  • Given the right conditions, these colorful fish can live quite long. While most koi breeds average 30-40 years, others like the legendary koi named Hanako, have reached more than 200 years old. 
  • They can get sunburnt, so either keep their tanks away from direct sunlight or provide a place of shade for them to hide under. 
  • They are believed to bring good fortune. Huge koi breeds and koi individuals have been sold for thousands of dollars. 


Photo by Anil Sharma

  • As aquarium fish, they are mostly bought for their cleaning abilities. Since catfish happily consume algae growing in the bottom and sides of the tanks, they effectively keep the aquariums relatively clean (at least for some time). 
  • They are not particularly colorful so keeping them in tanks is often not for ornamental purposes, but to help reduce algae.
  • They are low-maintenance fish. 
  • These fish can also breathe air.
  • There are also several types of catfish to choose from. Some are more colorful than others. 


Photo by zoosnow

  • They are pretty popular, but these magnificent fish are not for beginners. They require massive tanks and periodic exams since they are prone to infections – infections that inexperienced keepers can easily miss. 
  • They can grow really big. Some can grow as long as 40 inches and require even bigger swimming space. 
  • They are excellent hunters. They can swim fast (thanks to their very long and powerful tails), they can see very well (even if the prey is above water), and they can also jump high too (up to 2 meters above the water’s surface). 
  • They can be sold for a hefty price. Adult arowanas can be sold for more than 1,500 dollars. Big ones, especially with the rare colors, can go for as high as 12,000 or even higher. 
  • If you are up for a challenge, you can try this awesome hunter for your first fish. However, you better watch this care guide closely to have better success.


Photo by basuka

  • These small fish come in a variety of colors – perfect for adding different hues to your aquarium setup.
  • They reproduce quickly. Females are capable of storing sperm and then giving birth to other batches even if they’ve only been inseminated once. Without proper isolation and natural predators, they can quickly max out your tank capacity. 
  • They can live in various water conditions because they are highly adaptable. 
  • They are also omnivorous, capable of eating algae, insects, and almost anything that can fit in their mouth (including other guppies). In some countries, they are being introduced into different water pools to deliberately prey on mosquito larvae and fight off malaria. 


Photo by Ylanite Koppens

  • Freshwater angelfish, despite sharing plenty of similarities with their marine (saltwater) counterparts, are quite different from saltwater angelfish. They belong to two separate families – Pomacanthidae (marine) and Cichlidae (freshwater). 
  • They can be bullies against non-angelfish species in the tank. If you plan on keeping them in a community tank, make sure that the other tank mates are at least two inches in size so they won’t be attacked or eaten by the angelfish.
  • They are vulnerable to parasites, so watch out for signs of infestation. 
  • They are omnivores so they can feed on plants as well as shrimps, worms, insects, and other small fish. They can also do well with fish pellets, but not exclusively. 
  • They are a colorful addition to any aquarium especially since they come in different patterns and color combinations. 

Frequently Asked Questions

Are freshwater fish better for beginner fish hobbyists than marine fish?

Generally yes. Marine or saltwater fish have more requirements than their freshwater equivalents – narrower pH range, salinity levels, temperature, amount of UV exposure, and much more. Because of this, most people who take the courage to invest in marine setups are experienced fish handlers. 

Although no one is stopping you from trying a marine setup or a saltwater reef yourself, it would still be advisable (and prudent) to learn as much as you can from experienced keepers first. You can watch this video reference guide as a starter. 

How often do you need to change the water in your freshwater fish tank/aquarium?

Most freshwater setups can have a change of water weekly. However, you don’t need to change all the water at once. You only need to replace about 15% to 20% of the total volume in the tank with new clean water. Also, if you’re getting water from the tap, let it sit for 3 days first before using it to replace the one in your tank.

Which freshwater fish are good with sharing spaces in the tank (community tank)?

If you’re aiming to build a community fish tank and have different species inside, then you might want to start with peaceful fish species (least aggressive and non-territorial). Here are some examples of fish you can start with:

  • Guppies
  • Honey Gouramis and Dwarf Gouramis
  • Zebra Danios
  • Neon, Glowlight, and Diamond Tetras
  • Molly

It might also be a good idea to place fish that are relatively the same size because conflicts can arise between fish if one considers the other as possible prey. This becomes more unlikely if they all look the same size. 

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