With so many factors that go in to setting up your freshwater aquarium at home, selecting the perfect fish is at the top of the list!

Aquariums can make a stunning accent to any home – not to mention fish make the perfect pets.

They are quiet, easy to clean up after, and don’t require a lot of attention.

But, setting up an aquarium is about more than showing up at a pet store and pointing at the biggest and brightest fish. There are a lot of factors to consider when choosing the right fish for your freshwater aquarium.

Keep reading to learn all about fish selection and tank set up.

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Saltwater vs Freshwater

The first thing you need to know about selecting the right fish is whether you’re looking at saltwater or freshwater. Be sure to tell the associate at the pet store whether you’re creating a freshwater or saltwater tank, as the fish and plant life will be completely different.

You can look through a freshwater and saltwater coral guide to help you get an idea of which plants are best suited for each type of tank. It’s important that you don’t mix freshwater and saltwater fish or plant life, as putting them in the wrong tank will cause a very quick death. It is also important to keep the salinity at the right level, and you can use a salinity meter to monitor this.

Things to Consider:

Now that you found your freshwater selection, it’s time to narrow down the search. Here are a few things you should be considering before picking out your freshwater fish:


The fish and the pet store might look pretty small, but it won’t take long for them to start growing.

Fish stores often keep younger fish, first because they are cheaper and second because they can fit more in one tank. It’s important to know that whatever fish you get from the pet store will probably grow a decent amount. Some will stay small, but others can outgrow your tank in a matter of weeks. 

Talk to the experts at the pet store and find out how big of a tank you’re going to need to house each individual fish. 

Keep in mind that it’s not usually a good idea to keep small fish in the same tank as larger fish. The larger fish will likely munch on the little fish as snacks in between feeding times.


Diet may not seem like an important factor when it comes to choosing the right fish, but it can certainly make a big difference when you find yourself trying to organize feeding times for 6 different special diets.

Bigger fish will probably have a diet of smaller fish, whereas smaller fish might have a diet of bacteria, plankton, etc.

How are you keeping the bigger fish from eating the wrong type of food? How will they get their nutrients if they fill up on the wrong diet?

These are important questions you should be asking and considering before mixing and matching fish with different dietary needs. 


Speaking of munching, aggression is another thing you want to consider before picking out your fish.

Beta fish, for example, are well known as very aggressive -beautiful- fish. You can’t put two male beta fish in the same tank without an Asian style fight to the death. You can, however, have one beta fish and a few less aggressive tank mates like ghost shrimp, Guppies, African dwarf frogs, among others.

It might take a little bit of research and coordination to figure out which fish will make the best ecosystem in your tank.

ProTip: snails are like Switzerland. You can put them in a tank with just about anybody and they will get along. Snails are great for eating up algae growing on plants, gravel, or the sides of the tank.


Maintenance? Isn’t that what the filter is for?

Even though you have a good filter set up, it’s important to perform regular maintenance on your aquarium. This could mean brushing the sides of the tank with an algae scraper, and using an aquarium vacuum for cleaning gravel and replacing portions of the water.

Some fish require more maintenance than others. For example, goldfish are really dirty fish. They will need routine tank cleanings more often than other fish.

But what if you have some fish that aren’t very active and prefer the calm and quiet? Regularly stirring up the tank and stressing them out for several cleanings can send them into shock.

Water Temperature

If you’re thinking about filling your freshwater tank with a couple of gallons of tap water and leaving it at that, you won’t have and ecosystem for very long. To have everything set up right, you’ll need treated water and a good aquarium heater set to an appropriate temperature, as well as an aquarium thermometer.

What’s the appropriate temperature?

That depends on what type of fish you’re planning on keeping in your aquarium. Just like people, some fish thrive in a warmer climate and others prefer it colder.

ProTip: In theory, it may seem like a good idea to mix fish that prefer hotter climates and colder climates, and set the thermometer to a compromising temperature. Please do not do this. Your fish will not be happy and could quickly turn belly up. 

Freshwater Aquariums for the Win

Whether you’re looking to add some new life to your existing ecosystem or set up a whole new freshwater aquarium, the most important factor to get right is fish selection.

It won’t be long and those sweet little fishes will wiggle their little bodies and greet you when you come up to the tank. They will become your little fish babies and they will always be your little fish babies.

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