Saltwater Vs Freshwater Aquarium – What You Need To Know

If you’re keen to get into the fishkeeping hobby, you might be wondering whether a saltwater or freshwater tank would be best for you.

When it comes to freshwater vs saltwater aquariums, it’s widely believed that a marine tank is more difficult to keep and maintain, so that it wouldn’t be the best choice for a beginner. 

In this comparison, we look at the difference between saltwater and freshwater fish and discuss the pros and cons of a freshwater tank over the coral reef aquarium.

What’s the Difference Between Saltwater and Freshwater Aquariums?

As the names suggest, a saltwater aquarium contains saltwater, and a freshwater tank uses freshwater.

A saltwater tank can house tropical marine fish species, corals, sponges, anemones, and other organisms you typically find living in the ocean. 

In comparison, a freshwater tank is a home to coldwater or tropical fish species and aquatic plants that cannot tolerate salinity.

Saltwater Vs Freshwater Aquarium

Features

Saltwater

Freshwater

Water System

Saline

Freshwater

Maintenance (how many weeks)

Daily, weekly, and monthly, depending on setup and livestock

Weekly basic maintenance Monthly filter maintenance

Plants

No

Yes

Cost

More expensive to set up and stock

Less expensive to set up and stock

Equipment(s)

More equipment

Less equipment required

Saltwater

Water System

Saline

Maintenance (how many weeks)

Daily, weekly, and monthly, depending on setup and livestock

Plants

No

Cost

More expensive to set up and stock

Equipment(s)

More equipment

Freshwater

Water System

Freshwater

Maintenance (how many weeks)

Weekly basic maintenance Monthly filter maintenance

Plants

Yes

Cost

Less expensive to set up and stock

Equipment(s)

Less equipment required

What Are The Best Features Of A Saltwater Aquarium?

Probably the best thing about a saltwater aquarium is the variety of fish and other life that you can keep in one.

Coral Saltwater reef aquarium tank

As well as a plethora of unusual fish with beautiful vibrant colors, you can keep some spectacular shrimp, anemones, corals, and other creatures, depending on the setup you have.

What Are The Pros And Cons Of A Saltwater Aquarium?

There are a number of pros and cons to keeping a saltwater aquarium:

Pros

First, let’s take a look at the pros of a marine setup:

  • There’s a wide variety of brightly colored fish, invertebrates, corals, anemones, and other creatures to choose from.
  • You can create some truly beautiful aquascapes in a reef or marine tank.
  • Watching fish swimming in a well-maintained tank is scientifically proven benefits for your mental and physical health.

Cons

Unfortunately, the disadvantages of keeping a saltwater tank tend to outweigh the advantages: 

  • Saltwater aquariums are generally considered to be unsuitable for beginners.
  • Although very beautiful and fascinating to watch, marine fish are typically much more expensive to buy than freshwater species.
  • You need much more specialist equipment for a marine tank than you do for a freshwater setup, making the initial outlay much greater.
  • Saltwater holds around just 80% of the oxygen that freshwater contains. That means you’ll need a larger tank for marine fish than you would for freshwater species so that your fish can breathe.
  • A large aquarium must be kept on a purpose-built stand, which will take up a lot of space in your home, not to mention costing more to buy.
  • A marine tank typically needs more care and maintenance than a freshwater setup. You’ll have daily, weekly, and monthly tasks to carry out to keep the tank in good order, so you must be sure you have time for that level of commitment.
  • Some saltwater fish species are demanding when it comes to diet, and that often works out quite expensive both in terms of the cost of food and in the time it takes to prepare it.
  • Many species of marine fish and inverts are territorial and aggressive, so it’s not easy to create a harmonious community unless you have a very large tank with plenty of hiding places.
  • The correct levels of salinity and general water quality are essential for a healthy marine tank setup. That means you’ll need to monitor the water parameters daily and make any adjustments that are required.
  • Many species of saltwater fish are delicate and mortality rates can be high, which is particularly gutting given how much the fish cost to replace.
  • Algae is a nuisance in all fish tanks, but saltwater setups tend to grow algae very quickly, simply because there are no live plants to use the nutrients in the water and starve the algae.
  • Although beautiful, saltwater fish can be more temperamental and difficult to keep than freshwater species.Place a couple of inches of gravel or sand into the tank. Set an upside-down bowl on top of the substrate. 

What Are The Best Saltwater Fish For Beginners?

Some saltwater fish species are a better choice for a newcomer to the hobby than others. I recommend the following as suitable marine fish for newbies:

  • Clownfish
  • Dwarf Angelfish
  • Damselfish
  • Tangs

All these fish are brightly colored and fascinating to watch, and they are often not as expensive to buy as rarer species.

What Are The Best Features Of A Freshwater Aquarium?

There are hundreds of different species of freshwater fish and inverts that can be kept together harmoniously in a community setup.

A green beautiful planted tropical freshwater aquarium with fishes

Also, freshwater fish species are not typically as expensive to buy as marines.

What Are The Pros And Cons Of A Freshwater Aquarium?

Here’s what’s great and not so great about keeping freshwater fish:

Pros

  • Watching fish swimming in a well-maintained tank is scientifically proven to be beneficial for your mental and physical health.
  • Freshwater fish are generally considered to be a better option for beginners and can make excellent low-maintenance pets for kids.
  • Tropical and coldwater freshwater fish are much cheaper to buy than marine species.
  • The initial cost of setting up a freshwater tank is much lower than that for a saltwater tank because the setup is much more basic.
  • You can successfully keep many species of nano fish in a very small tank. That means you can still enjoy fishkeeping even if space in your home is limited.
  • If you opt for a small tank, you may be able to keep it on a desktop or counter, so you won’t incur the additional expense of an aquarium stand.
  • Maintenance of a freshwater tank is pretty basic, requiring only weekly water changes and monthly filter maintenance.
  • Most freshwater fish are easy to please when it comes to diet and nutrition, making them relatively cheap to feed.
  • There are dozens of tropical and coldwater freshwater fish that can be included in a peaceful, harmonious community setup.
  • You can keep living plants in a freshwater tank. Plants help to maintain the water quality by utilizing nitrates, which can also keep algae under control.

Cons

  • Freshwater fish aren’t generally as brightly colored or unusual in shape and form as marine species.
  • You need to devote around an hour a week to general tank maintenance tasks.

What Are The Best Freshwater Fish For Beginners?

Here are a few of the best freshwater fish species for beginners:

  • Betta fish
  • Cichlids
  • Common goldfish
  • Tetras

These fish are all fairly straightforward to keep and are reasonably priced, too.

Saltwater Vs Freshwater Aquarium Cost

So, how does the cost of setting up a saltwater tank compare with that of a freshwater aquarium? Let’s find out.

Here are the approximate costs of everything you need to get your tank up and running.

Materials

Saltwater Tank

Freshwater Tank

Tank

$50

$50

Sand or gravel substrate

$45

$20

Live rock

$100

N/A

Salt

$25

N/A

Filters

$25

$50

Powerheads

$50

Optional

Protein Skimmer

$150

N/A

Lighting Unit

$50

$50

Water Testing Kit

$70

$50

Quarantine Tank

$25

$25

Heater

$15

$15

Total Cost

$590

$245

Saltwater Tank

Tank

$50

Sand or gravel substrate

$45

Live rock

$100

Salt

$25

Filters

$25

Powerheads

$50

Protein Skimmer

$150

Lighting Unit

$50

Water Testing Kit

$70

Quarantine Tank

$25

Heater

$15

Total Cost

$590

Freshwater Tank

Tank

$50

Sand or gravel substrate

$20

Live rock

N/A

Salt

N/A

Filters

$50

Powerheads

Optional

Protein Skimmer

N/A

Lighting Unit

$50

Water Testing Kit

$50

Quarantine Tank

$25

Heater

$15

Total Cost

$245

So, you can see that setting up a saltwater aquarium is going to cost you roughly twice what a freshwater tank would.

Also, you might only want a small tank, which will be considerably cheaper to buy than the 75-gallon minimum aquarium that you need for a marine setup. Smaller tanks often come in kit form, so you won’t need to buy separate lighting units, filters, and heaters.

What About Fish?

Now you need to factor in the cost of stocking your tank with fish. 

The cost of the fish and inverts you choose will vary depending on the rarity and size of the species. 

You can generally buy most freshwater fish from a few dollars to around $10 per fish, and you often get deals on buying a group of fish, which is ideal for species such as tetras that naturally live in schools.

However, marine fish prices can start from $20 and upward. Basically, the sky’s the limit!

Running Costs

The running costs of freshwater and saltwater tanks are fairly comparable in terms of electricity. However, water testing kits for marine tanks are pricier than those for freshwater tanks. Also, you will need to buy salt for a marine tank, whereas you don’t need that for a freshwater setup.

Saltwater Vs Freshwater Aquariums Myths

Freshwater Aquariums Are Easier To Keep

Essentially, freshwater tanks are easier to maintain and keep healthy than saltwater setups.

How so?

Well, the oceanic environment tends to be much more stable than that of a freshwater river, lake, pond, etc. In the ocean, the pH and salinity remains pretty constant. However, in comparison, the water chemistry in a freshwater environment is constantly changing, perhaps due to seasonal changes such as drought or flooding.

So, freshwater fish species tend to be hardier and more forgiving of fluctuating water conditions than their saltwater cousins.

Saltwater Tanks Aren’t Suitable For Beginners

To a certain extent that’s true. 

Saltwater fish and the equipment you need to keep them is more expensive than the freshwater equivalent. Beginners tend to make mistakes and fish mortality is common, so you could lose a lot of cash if you get it wrong.

Saltwater tanks can be complex, depending on whether you want to keep:

  • Fish only
  • Fish with live rock
  • Reef

A fish-only tank is relatively straightforward, whereas a reef setup is very complex.

As previously mentioned, a marine tank needs to be larger than a freshwater one. So, maintenance requirements are more time-consuming.

All that said, if you start with a fish-only 75-gallon tank, pick an easy beginner fish species, and you’re diligent with your maintenance, it is possible for a beginner to keep marines.

A Saltwater Tank Can’t Convert To A Freshwater Aquarium

Yes, you can convert a saltwater tank to a freshwater one.

All you need to do is remove all the equipment and give the tank a thorough clean with dechlorinated water. Pay particular attention to removing accumulations of salt from the tank surfaces.

You Can Breed Saltwater and Freshwater Fish In Captivity

Most saltwater fish are wild-caught, which is one of the reasons they are so expensive to buy. 

That’s because breeding marine fish in a captive setting is notoriously difficult. Saltwater fish breed seasonally, and that can be extremely challenging to recreate in the aquarium.

In contrast, many species of freshwater fish spawn readily in the home tank. So, a beginner can have lots of fun watching their fish produce eggs and live fry.

So, if you’re interested in breeding your fish, I recommend you choose a freshwater setup.

Algae Is A Bigger Problem In Saltwater Aquariums

That’s true!

Algae Is In all aquariums, the water contains nitrates that are created during the nitrogen cycle. Algae use nitrates as a nutrient source. Plants also absorb nitrates from the water, but living plants will only survive in a freshwater environment. Therefore, in a freshwater tank that contains live plants, algae are starved of the essential nutrients they need and cannot grow and spread as easily.AThat’s true! Bigger Problem In Saltwater Aquariums

Saltwater Aquariums Must Be Bigger

That’s partially true.

How so?

Saltwater doesn’t hold as much oxygen as freshwater. Therefore, you need a larger tank that provides a greater surface area for maximum gaseous exchange. So, you can’t keep as many fish in a saltwater tank, simply because there isn’t enough oxygen to support them. 

Also, in a freshwater tank, you can include lots of plants. Plants produce oxygen and absorb CO2 through photosynthesis, helping to oxygenate the water for the fish.

So, if you want a small tank or lots of fish, a freshwater tank is a better choice.

In Conclusion

A green beautiful planted tropical fish tank.

If you’re a beginner and you want a small tank with quite a few colorful, hardy fish, a freshwater tank is the way to go. A freshwater setup is also cheaper to buy and run, as well as being less time-consuming in terms of maintenance. You could even breed your fish if you want to.

Aquarists with more experience and time available to devote to tank maintenance might enjoy the challenge of keeping saltwater fish. You’ll need plenty of space to accommodate a larger tank, and you won’t be able to keep as many fish. However, you have more species to choose from and most are much more vibrantly colored and interesting to keep. The biggest downside to marines is that the fish can be very expensive and tend to be more fragile than freshwater species.

Do you have a freshwater or saltwater tank? We’d love to hear about your aquarium! And please ask any questions you have in the comments box below.

Interested in different aquarium setups? Click here.

Alison Page has been an avid fish keeper for over 35 years and has owned many different species of freshwater tropical fish including bettas. Currently Alison has two large freshwater tanks. The first tank has two huge fancy goldfish who are almost ten years old and still looking as good as ever. In the other, she has a happy community of tiger barbs, green tiger barbs, corydoras catfish, platys, and mollies.

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