Can you change a freshwater aquarium into a saltwater aquarium?

Can you use any fish tank for either type of aquarium?

What do you need to change the habitat from fresh to salty? 

The answers: Yes, you can switch the type of aquarium, and just about any fish tank will do.  The only challenging factors may be about the livestock itself.

Changing a Freshwater Aquarium into a Saltwater Aquarium

If you’re planning on starting a saltwater aquarium, any glass or acrylic fish tank would be ideal. Therefore, the tank you already use for a freshwater aquarium should do just fine.

If you plan to use your existing tank, you would need to move your existing livestock into a temporary tank before you begin designing the main tank as a saltwater aquarium. The temporary tank can have only the bare minimum, but it should be safe and enjoyable for the pets for the time being. For instance, you may wish to place a couple items of artificial decor as well as lay gravel, and you should monitor the temperature and pH level of the temporary tank. 

Alternatively, invest in a new tank to make the switch easier on yourself, and when it’s all said and done, you can keep your existing tank as a backup or quarantine tank. (Learn how to set up a quarantine tank here.)

Once you make these choices and complete those steps, you’re ready to design your new saltwater aquarium. To make the change, you will only need the essentials. See our past blogs for details, but the basics you need for a saltwater aquarium include:

• A durable tank that is of a suitable size for your anticipated design and future inhabitants’ needs
• A heater, which is sometimes optional for freshwater tanks but is a must for saltwater aquariums
• Lighting elements
• RODI water (mixed with your preferred brand of salt)
• Mechanical filtration systems
• Natural filtration elements
• Gravel
• Plants

Optional but highly recommended additional elements include artificial or live rock, bottom feeders, and decor.  They will add intrigue to the tank as well as provide shelter and entertainment for the animals.

If you’re designing a reef tank, coral must be included as well.

The Livestock

Installing and designing the tank itself shouldn’t be too difficult, but your ability to change a freshwater aquarium into a saltwater aquarium will depend on the livestock.

Do you have existing fish, or are you planning to buy new pets? What types of fish do you have? If you’re planning to add new fish when you get your saltwater habitat set up, will they be compatible with your existing fish? What about the plants?

All of these are very detailed issues best discussed one on one with our aquarium pro, Jimmie, but we’ll try to address the basics here.

Brackish/Euryhaline Fish

Many fish can live in saltwater, freshwater or brackish water, and they’re known as euryhaline fish. If you own these, you should be able to acclimate them to your saltwater habitat. (Learn how to introduce a new fish into an existing habitat here.)

Common euryhaline/brackish fish include various species of guppies, gobies, catfish, and mollies. (Learn more about the versatile molly fish here.)

If you currently have brackish fish, therefore, you’re probably in the best position. (Is this phrase new to you? Learn more about brackish fish here.)

Freshwater Fish that Only Live in Freshwater Habitats

You won’t be able to move certain species of freshwater fish into a saltwater aquarium. You may have to opt for two separate tanks: one freshwater and one saltwater. (Nothing wrong with that, right? The more the merrier!)

Tropical freshwater fish, for example, can’t live in saltwater at all. 

Live Plants

You should be able to replant live plants into the saltwater aquarium with no problem, as long as you use the proper methods of moving and planting plants.

Filtration Systems

Technically you can use the same filters, but saltwater tanks typically require stronger and more comprehensive filtration systems. When you first change your freshwater aquarium into a saltwater aquarium, your existing equipment may be good enough. Later, you may wish to add additional elements or buy more adequate solutions.

For assistance in installing your new saltwater fish tank or designing the aquarium, call us for a design consultation!