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Can River Fish Live In a Tank? Compatibility and Tips

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A few years ago, I purchased a large aquarium for my home, and I filled it with colorful fish from my local pet store. It was a nice addition, but the fish were tiny, and they didn’t look anything like the beauties swimming in the rivers and streams around my home. The realization got me wondering why tanks always display exotic fish rather than more sustainable native game fish.

River fish can live in a tank, but there may be challenges. Some species require a very large tank and do not do well with tank mates. However, if you can select the right types of fish, provide them with the right environment, and care for them well, you can succeed with a river fish tank. 

In this article, I’ll cover these topics in great detail. I’ll also discuss several related issues, including legal concerns, potential health issues, and some tips for setting up your river fish tank for success. 

Can You Keep River Fish in an Aquarium?

Freshwater fish are among the most common pets in the United States, with over 12.5 million households keeping these swimmers on display. There is a booming industry for purchasing freshwater fish for aquariums. However, people who live near rivers, streams, and lakes may have an abundance of fish free for the taking. 

You can keep river fish in an aquarium as long as the tank is big enough and the species is suitable for aquarium life. Some river fish grow too large for a tank, and others have special dietary or other needs that are difficult to maintain. River fish should have their own tank. 

It’s essential to have a good understanding of the species before you determine whether you should keep a river fish in your aquarium. 

Best River Fish For Aquariums

The best river fish for aquariums will be the appropriate size (meaning, they won’t grow into massive adults that are too big for the tank), amenable to living with other fish, and easy to care for. While tropical fish are often known for their bright colors and lively swimmers, what you can find among river fish may surprise you.

White Cloud Mountain Minnow

Source: Dreamstime stock photos

Before you start your collection, it’s a good idea to learn all you can about the species populations to make sure that you only gather fish suitable for aquarium life. Once the fish live in your tank, you should never release them back into the wild. 

In many areas, it’s illegal to do so, but it’s also unethical as the fish will no longer be able to defend itself or care for itself in the wild. Doing so is also potentially damaging to the ecosystem, so make sure that you know what you’re collecting before you take it home.  

Best Fish Groups for Your Tank

CentrarchidaeSunfish, bluegill, pumpkinseed, largemouth bass, crappiesVery common in North America, able to thrive in captivity. Some are too big for a tank, such as largemouth bass. 
Percidae DartersMany are bright and colorful. “Dart” quickly through the water, making them fun to watch. Small size works well for a tank.
CyprinidaeCarp, minnows, barbs, barbelsExtremely common, will survive with any other fish that are not natural predators. Also called “shiners,” some minnows are colorful during spawning season and others have a nice shine.
IctaluridaeCatfish, madtomCatfish are too big and will become predators – do not add these to your tank. Madtoms look like mini catfish. The tadpole madtom is a popular aquarium addition, but they are nocturnal. 

Species and Compatibility 

Many wild-caught or captured fish may be more aggressive than others when it comes to placing them into a tank with other fish. This is another reason you should not put river fish into a tank with exotic or tropical fish. The small, colorful swimmers will likely become the larger fish’s next meal.

Even the gentle, unsuspecting tadpole madtom is known to swallow anything that it can fit in its mouth. This may include smaller fish that are getting their rest while the nocturnal madtom feeds. 

To prevent any unwanted losses, it’s important to research any species carefully you add to the tank to ensure that they will be compatible with the existing population.

Here are some questions to answer before you collect your river fish:

  • How big will the fish get?
  • What does it eat?
  • What are its natural predators/prey?
  • What types of fish will it get along with?
  • What temperature and water condition does it need?

How to Acquire River Fish

Anyone who decides to have a native freshwater fish tank may be unsure of the best way to acquire the fish. Retailers typically don’t sell these varieties, and local hatcheries usually just produce game fish. You may have some luck at a smaller store specializing in aquariums and has a large variety of fish, but the local types will probably be very limited. 

Many people decide to collect their own fish from local waterways, especially if they spend time fishing and are familiar with the most common types. If you have access to a river and want to get your hands wet, make sure you do your homework before you head out with your nets. 

Legal Restrictions and Regulations

Before collecting fish from the wild, take some time to research any local or state regulations. There may be restrictions on which species you can take during certain times of the year, rules about how you’re allowed to collect fish, and information about which species are protected or endangered. 

For example, according to the Florida Fish and Wildlife Conservation Commission, freshwater fish are either “game” or “nongame” varieties. Game fish include various bass, sunfish, bluegill, crappie, and flier. These may only be taken using a fishing pole and line or rod and reel.

Nongame fish are all other fish that aren’t defined as “game,” except for grass carp and alligators. Nongame fish may be taken in various ways, including nets in most areas, traps, setlines, trotlines, and others. 

Most regulations are determined by the individual states, as the states own and govern the land and waterways for public use. However, some federal laws, including the Endangered Species Act, could apply to certain fish. You should always ensure that you correctly identify a fish before collecting it. 

In addition to these, there are local and state licensing requirements to familiarize yourself with before heading out to the water. 

Regulations Around the World

These same kinds of laws and restrictions may be found in all parts of the world, so it’s always a good idea to check with local authorities or do some research before heading out to the river wherever you are.

Here are some examples of the kinds of legalities to be aware of: 

  • Germany and Switzerland: It’s illegal to fish without the intent of keeping the catch. It’s also illegal to release a fish that is eligible to keep. 
  • British Columbia: Licensed guides cannot take non-residents to certain rivers. The law was intended to reduce illegal guides. 
  • Australia: It’s illegal to use the ancient “tickling” technique to subdue trout by rubbing their bellies.
  • Iceland: Local customs prohibit skipping rocks on the water. 
  • England: Anglers must cast upstream while fishing on various chalk streams and rivers, such as the Test and Itchen.

River Fish Health and Safety

Many wild fish can carry diseases and parasites, but it isn’t a problem if they are kept in their own tank with other fish from the same environment. For this reason, you should never mix river fish with tropical or other exotic fish from a pet store. Doing so could cause the tropical fish to become sick and die.  

When adding new river fish to the tank, it’s a good idea to quarantine them in their own aquarium for two to four weeks to avoid introducing any diseases to your existing population. 

Tips for Your River Fish Tank

A river fish tank can be a beautiful and exciting project. Filling it with native fish is a rewarding experience, especially if you learn about the species and collect them yourself. Once you do all the work of acquiring your fish, you will want to ensure that you’re set up for success. 

Do some research ahead of time to learn how to properly maintain an aquarium, when and how often to feed your fish, how and when to clean the tank, and so on. It will save you a lot of headaches in the future. 

Water Condition

The good thing about freshwater fish is that they live in dynamic environments that change with the seasons. However, you will need to ensure that the water condition in your aquarium is suitable. This includes temperature, pH, and cleanliness. 

Never fill your aquarium with plain tap water. Chlorinated tap water can kill your fish. You may need to add a chiller to keep the tank’s water at the correct temperature, so make sure to research what temperature each species requires. 

Mimic the Natural Environment 

For the best transition, it’s helpful to try to mimic the fish’s natural environment as much as possible. If the fish naturally likes to hide in rocks, for example, it would be a good idea to provide that element in your tank. 

The water temperature, depth, and amount of sunlight are all things to consider when setting up your aquarium. Happier fish will be healthier fish. 

How to Determine What Size Tank You Need 

Having a big enough tank is one of the most critical components of a river fish aquarium. Before you begin, you’ll need to know how big your fish will get and how many you plan to have. Or, if you already have the tank, you’ll need to make sure to only select fish that are appropriate for the tank’s size. 

In general, you should have at least one gallon (3.8 L) of water for each inch (2.5 cm) of fish. If you plan to add rocks, plants, or other structures, you’ll need to take that into account as well. It’s best to start with just a few fish (three or less) to see how they do before adding more. 

Source: Dreamstime Stock Photos

Caring for Your River Fish

Keep a close eye on your river fish for the first few weeks to see how they do in their new environment. One thing you can do to help them thrive is to keep the water clean and fresh. Some species of fish may produce a significant amount of waste. To keep the tank clean, it’s important to check the filter often and clean it every few days. 

Try to make sure that the light is similar to what the fish experience in the wild. They should get several hours of light and several hours of dark to help maintain their natural processes and rhythms. 

Something else to consider is that river fish, especially if collected from the wild, may reproduce on their own and overpopulate the tank. If possible, try to identify males and females to keep them separate. A quick web search may provide some identifying features such as color or pattern differences, variations in the fins, or typical sizes of males versus females. 

What to Feed River Fish

Knowing the species you have in the tank, and their dietary needs is essential to keeping your fish happy and healthy. However, just being familiar with the environment where they live naturally will help you make good decisions about what they can eat.

Some crowd-pleasing options are earthworms, shrimp, algae, crickets, prawns, flake or pellet fish foods, or bloodworms. Most fish will eat frozen or pellet foods, which is a more convenient and economical option. 

Watch for any signs of illness or fish that may not be getting enough access to foods so that you can separate them into a different tank if needed. 

Final Thoughts

Collecting river fish for a native aquarium can be an exciting and rewarding project. The technologies available today make it possible to create a small version of a large ecosystem for you and your family to enjoy and learn from for years to come. 

If you take the time to learn about the different species and their needs, you can grow a collection of beautiful and lively river fish while doing your part to keep them happy and healthy. Providing a large enough tank with the right conditions and care will allow these beauties to thrive in a river aquarium.


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