Freshwater vs Saltwater Fish Tank (Find out which one is best)

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The very first decision you will need to make is whether you would like a freshwater vs saltwater fish tank.

Both types come with many advantages and disadvantages.

There are also differences in terms of maintenance, types of fish and setup costs.

This article will help you to decide which type is best for you.

If you are just starting out and want to buy your first aquarium then I highly recommend that go for a freshwater tank.

They are easier to maintain, are more forgiving with mistakes and the fish are generally cheaper to buy.

Freshwater tanks can be made from glass or acrylic and come in many shapes and sizes.

As far as freshwater fish is concerned, you will be spoilt for choice and they are not as expensive as saltwater fish.

You can create a tank set up for a specific species of fish to mimic their natural habitat, a full CO2 planted tank or a general community tank with the fish interacting with each other.

Freshwater aquarium

Cold Water or Tropical Fish Tank

Freshwater fish tanks can be either cold or tropical.

Cold Water Fish

The water in cold freshwater tanks (Below 68°F (20°C) does not need to be heated and you will find a decent amount of different species that you can choose from.

What fish can live in cold water tanks?

Goldfish are the most common cold water fish but just bear in mind that Goldfish are messy fish and do require a larger fish tank to handle the waste.

Comets, Shabunkins and the common goldfish need at least 20 gallons of water per fish.

Fancy goldfish should have at least 10 gallons of water per fish.

Goldfish in aquarium

Other cold water fish

Freshwater crayfish

Does a cold water fish tank need a filter?

Yes, they do especially if the tank is housing goldfish.

Some fish keepers do not have a filter in their cold water tanks but then they need to do almost daily water changes to keep the water in good condition.

Fish produce waste which needs to be removed. They actually pee and poop just like us humans.

A filter will ensure that the water is kept clean and it will also house beneficial bacteria that will help break down the toxic waste.

Tropical Fish Species

Tropical fish live in warmer water with temperatures ranging from 76 to 80 degrees Fahrenheit. (24.5 to 26.7 degrees Celsius)

There are a huge number of different species with various forms within them as well.

Here are just a few of the main species:

Guppy fish

And then some unusual fish like:

  • Knifefish
  • Puffer
  • Half Beaks
  • Gudgeon
  • Goby
  • Flagfish
  • Silver Dollar
  • Eels
  • Badis
  • Butterflyfish
  • Elephant Nose
  • Ghost Catfish
  • Rope Fish
Puffer fish

What are the best tropical fish to start with?

I would suggest going for some live bearers like guppies, mollies and platys. 

Add a few cory catfish to help keep the substrate clean and lastly have a small school of neon tetras to bring even more color to your tank.

What is the most beautiful tropical fish?

This can be a very subjective choice.

My favorites are Dwarf Gourami, German Blue Rams, Apistogramma and freshwater Angelfish.

German Blue Ram

Saltwater fish

Saltwater fish are normally vibrant and very colorful.

There are also main species just like with freshwater fish.

These include:

  • Dwarf Angelfish
  • Large Angelfish
  • Anglers
  • Frogfish
  • Anthias
  • Basslets
  • Blennies
  • Boxfish
  • Butterflyfish
  • Cardinalfish
  • Chromis
  • Clownfish
  • Damselfish
  • Dartfish
  • Dottybacks
  • Dragonets
  • Eels
  • Filefish
  • Foxface
  • Gobies
  • Groupers
  • Grunts
  • Hawkfish
  • Hogfish
  • Jawfish
  • Lionfish
  • Pipefish
  • Puffers
  • Rays
  • Scorpions
  • Seahorses
  • Sharks
  • Squirrelfish
  • Tangs
  • Triggerfish
  •  Wrasse

Is a saltwater tank harder to maintain than a freshwater tank?

The ocean is a vast expanse of water. What this means is that it does not change much at all and the water chemistry is stable and consistent.

The living conditions of saltwater fish are therefore constant day in and day out.

Compare this to freshwater fish that are found in lakes, rivers, dams and streams.

These environments are subject to seasonal change and environmental occurrences like drying out, rain or flooding. These changes have an impact on the water chemistry and temperature.

Because of this, the freshwater environments are inconsistent and vary from time to time.

Freshwater fish have learnt to adapt to a wide range of water conditions and chemistry.

Freshwater fish are therefore much hardier and can withstand any small mistakes you might make to the water chemistry.

Saltwater fish, on the other hand, cannot tolerate changes to their environment and need very precise water conditions.

Saltwater fish are much more sensitive and it can prove lethal to them if the water chemistry varies too much.

For this reason, freshwater fish tanks are generally easier to keep if you are a beginner.

But if you fully understand how the nitrogen cycle works and how to test and do water changes then a beginner can start with a fish-only saltwater tank.

It is when live rock and corals are added to a saltwater tank that things become more difficult and are not recommended for beginners.

Saltwater Aquarium

Can you use a freshwater tank for saltwater?

Yes, you can use a freshwater tank and turn it into a saltwater tank.

Some changes will need to be made such as changing the filter, adding a protein skimmer and some powerheads for circulation but it can be done.

Are saltwater tanks more expensive?

Yes, they tend to be for four main reasons.

  • They need more equipment than a freshwater tank
  • You will need to buy live rock
  • You need to either make salt water (RO water and marine salt) or buy readymade salt water
  •  The fish and corals are more expensive than freshwater fish and plants

The costs work out to roughly double the cost if you want a saltwater tank.

Conclusion about freshwater vs saltwater

I have kept and keep both freshwater and saltwater tanks and my advice to you is to start with a freshwater tank.

Make your mistakes and learn what you need to learn.

Saltwater tanks are too unforgiving and things can go wrong so quickly.

As mentioned above, you could start with a fish only saltwater tank but it won’t be the same as having a tank with live rock and corals. It will look bare and you will soon feel disappointed.

Start with a 20 gallon freshwater tank so that you can have a decent amount and variety of fish and see how it goes.

Next Step

After choosing which type of fish tank you would prefer, then you will need to make a list of equipment to buy. 

Photo of author


Irma Bense is the founder of She has over 42 years of experience in keeping fish.She has kept both freshwater and saltwater fish through the years.She has extensive knowledge in breeding numerous species of fish from Show Guppies, Cory Catfish, German Blue Rams to Apistogrammas.You can learn more about Irma on the 'About' page.

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