Saltwater vs Freshwater Aquarium: All 9 Differences Explained

Are you wondering about saltwater vs freshwater aquarium? From a glance it is easy to tell the difference between a freshwater aquarium and a saltwater aquarium. Freshwater aquariums usually have an abundance of plants and have popular fish like Tetras and Bettas. Whereas saltwater aquariums usually have a UV light, coral reefs and vibrant fish.

However, the choice between a saltwater or freshwater aquarium is one the most important decision a fishkeeper. In this article we will explain the differences between a freshwater and a saltwater aquarium and also the pros and cons of each…

Saltwater vs Freshwater Aquarium

Saltwater vs Freshwater Aquarium Differences

Let’s start with the basics. Saltwater aquariums contain salt and freshwater aquariums have no salt. For reference a freshwater tank will have a salt content that is less than 1ppt, whereas a standard saltwater tank will have a salt content of around 34-36ppt.

A freshwater aquarium contains species that are found in lakes and rivers, including a variety of plants of other freshwater invertebrates like snails and shrimp. Whereas saltwater aquariums house a snapshot of what is contained in the ocean. This includes marine fish, corals, anemones and other saltwater species.

When it comes to saltwater vs freshwater aquariums most people just think about what types of fish or aesthetic they are trying to create. However the two main differences to consider are cost and maintenance. Saltwater and freshwater aquariums have very different maintenance requirements. Generally it is agreed that saltwater aquariums are much more difficult to maintain.

With saltwater the water parameters (like salinity and pH) are generally stable since their is so much water in the ocean. This means rapid changes in water parameters is not possible. Therefore, marine life has evolved to survive in fairly constant water conditions. So in a saltwater aquarium you will be spending large amounts of time to stop water parameters from fluctuating.

Whereas in freshwater, water parameters are constantly changing. These fish live in rivers and lakes and their water parameters can change greatly with rainfall, droughts, or flooding. This means that freshwater fish have evolved to be a lot hardier and forgiving as they are used to fluctuating water parameters. This means that conditions can fluctuations within a freshwater aquarium without such serve consequences.

Now let’s look at the differences in cost.

Saltwater aquariums will generally cost more. This is because they require much more equipment for the tank, including: powerheads, protein skimmers, saltwater testing kits, marine salt, live rock and even the fish. These aquariums also tend to be larger than freshwater aquariums. A larger tank size helps to maintain water parameters however it comes with more upfront costs, including the cost for a larger aquarium, stand and a stronger filter. Whereas with a freshwater aquarium they need less equipment and the fish tend to be cheaper too.

Finally let’s look at the differences in fish between the two different water types. Most marine species are more vibrant than freshwater fish. Marine fish have more varied and brighter colors. With saltwater setups you also have reef aquariums which can accommodate anemones and coral reefs which are also visually impressive.

This is not to downplay freshwater fish though. They are stunning in their own right and can come in a variety of shapes and colors. Planted freshwater aquariums are also a visual spectacle!

Freshwater Aquariums Explained

Freshwater Aquarium

Freshwater aquariums are by far the most popular option for beginners.This is because freshwater fish are more readily available and the tanks are cheaper and easier to maintain. Some of the most popular freshwater fish to keep include: Bettas, Goldfish, Tetras and Cichlids.

Freshwater aquariums uniqueness is their accessibility. You can find aquariums in pretty much any size and shape. Also just about anyone can keep a freshwater aquarium due to their low maintenance. Freshwater fish also tend to be more forgiving, so any mistakes that may occur tend not to be too severe. For a typical tank you can expect to spend a 1-2 hours per week taking care of fish – this includes weekly water changes and the monthly filter maintenance.

With a freshwater aquarium you will need to consider the initial set up costs which includes: the aquarium, lighting, set up (e.g. gravel, caves, plants) and of course, the fish. Freshwater fish tend to be cheaper and many popular varieties only cost around $5 each. Ongoing costs include electricity, food, testing kits and water conditioner.

Pros and Cons


  • Beginner friendly: Most people start with a humble freshwater aquarium as their first tank. This is because of their versatility and low care requirements. With freshwater you do not have to worry about keeping track of the salt content or the dissolved oxygen content.
  • Size options: For freshwater aquariums it is very common to keep small aquariums and even nano tanks. Such aquariums are perfect for people who live in apartments or for people who do not have much floor space.
  • Low maintenance: Maintenance for a freshwater aquariums is much simpler and easier than a saltwater aquarium. Also freshwater fish tend to be much easier to feed and have simple diets.
  • Low costs: Freshwater fish tend to be cheaper on average when compared to saltwater fish. Freshwater aquariums tend to also need less equipment which helps to keep the cost down.


  • Less colorful fish: Although some freshwater fish have appearances that rival marine fish, in general freshwater fish tend to be less vibrant and colorful than saltwater fish.
  • No coral reefs: At some point most fishkeepers will want to keep a beautiful coral reef. This is not possible with freshwater aquariums.
  • Complacency: Since freshwater fish are so hardy they can often survive in subpar conditions. This can sometimes lead to complacency and bad habits since you can get away with mistakes.

Saltwater Aquariums Explained

Saltwater Aquarium

Saltwater aquariums are a great choice if you want to keep some of the most colorful and beautiful fish in existence. A well maintained saltwater aquarium is fairly rare.

The variety of colors and interesting aquarium layouts are very different when compared to the more common freshwater tanks. Some of the most popular saltwater fish are: Clownfish, Green Chromis, Gobies, Dwarf Angelfish and Cardinal Fish.

However, these marine fish are a rite of passage. In order to keep these beautiful fish you must be able to successfully deal with the additional difficulty and maintenance. The main difficulties with keeping a saltwater aquarium are water changes and introducing fish.

Tank maintenance for a saltwater aquarium is a lot more involved. It is not uncommon for people to check their aquariums multiple times a day to make sure everything is running smoothly. A lot of work goes into keeping the water parameters constant and adding and mixing salt in the water is more involved than you might think.

You can also expect saltwater aquariums to be more expensive too. This is because they often need specialized equipment like powerheads and protein skimmers. Live rock is also needed to help with the filtration of the aquarium – this is another add on cost and the price varies depending on the type of rock you chose.

Pros and Cons


  • Beautiful fish: Saltwater fish tend to have more vibrant colors and varied shapes. Most people rarely get the chance to see marine life so seeing these fish up close is breathtaking.
  • Unique invertebrate: With saltwater aquariums comes the ability to keep interesting organisms like corals and sea anemones. These invertebrates are only available for saltwater aquariums and are fascinating to see.
  • Different fish: Almost everyone knows what a Goldfish or a Betta looks like. However with saltwater aquariums you can keep rarer fish like gobies and tangs.


  • Not beginner friendly: While beginners can keep saltwater aquariums they are certainly harder to keep than freshwater aquariums. Mistakes are more likely to happen in saltwater environments.
  • Larger Aquariums: Saltwater has 20% less dissolved oxygen in the water when compared to freshwater. Because of this you will need a larger aquarium if you want to keep the same amount of fish.
  • More expensive: Saltwater fish and equipment are both more expensive than their freshwater counterparts.
  • Fragile environments: In the marine environment the water parameters stay fairly constant. Therefore, the conditions in your tank must stay constant too – sudden changes can be devastating.

Frequently Asked Questions

Is A Saltwater Tank Harder To Maintain Than A Freshwater Tank?


A saltwater tank has more water parameters to keep track of. This means that they are slightly harder to maintain than a freshwater aquarium.

Also saltwater aquariums tend to be larger (due to the decreased amount of dissolved oxygen available) so they require more work.

Is A Freshwater Tank Cheaper To Maintain Than A Saltwater Tank?

Freshwater aquariums are cheaper to run than saltwater aquariums.

This is because buying saltwater is expensive and the food costs for saltwater fish and reefs can also add up as well. These ongoing costs do not apply to freshwater aquariums.

Can A Beginner Keep A Saltwater Tank?

Beginners can certainly keep a saltwater tank.

They just need to be aware that they are more expensive and harder to keep than a freshwater aquarium.


If you are new to fishkeeping then most beginners go with a freshwater aquarium because of the low maintenance and hardy fish. Freshwater fish come in a diverse variety of shapes and sizes so there is bound to be a fish that appeals to you.

Saltwater aquariums are a lot of work but these efforts do not go unrewarded. Saltwater aquariums offer some of the most striking fish and tank environments that will be sure to amaze anyone who views them. The choice between the two aquarium types is one of the most important steps to take. Therefore it is best to know what you are getting into before you take the plunge.

Do you have any questions between saltwater and freshwater aquariums, then let us know in the comments section below…