Can Guppies Live in Saltwater?

guppies saltwater

Are you interested in putting your guppies in a saltwater tank?

It’s a surprisingly common idea – guppies would look great in a saltwater tank because of their beautiful colors.

I’m happy to report that, yes, guppies can live in saltwater that is 150% more saline than seawater. In fact, guppies are a brackish water fish, so they do great in saltwater. Feel free to add some fancy guppies to your saltwater tank.

However, you can’t just dump guppies from a freshwater tank into a saltwater tank and expect them to survive. This article will cover the proper way to add guppies to a saltwater tank.

Guppies Live in Brackish Water in Nature

First of all, guppies naturally live in brackish water.

That’s right, guppies are not a natural freshwater fish. They can obviously live in freshwater because they’re a hardy fish, but they really thrive in brackish water.

For those that don’t know, brackish water is a mix between seawater and freshwater. It’s normally found in swamps, river deltas, and other areas where freshwater from rivers meets the ocean.

Furthermore, guppies are an extremely hardy fish. As mentioned in the introduction, guppies can live in water 150% saltier than seawater.

Excuse the French… it is absolutely insane that a fish can live in freshwater or water 150% saltier than seawater.

With that in mind, your guppies will be fine in a saltwater tank unless you’re saltwater tank has the same saline content as the Dead Sea.

Acclimatization is Key

Ok, I hinted at this earlier. You can’t dump guppies from your crystal clear, low mineral freshwater tank into a reef tank.

That is a recipe for disaster. Why?

Acclimatization. Your guppies have spent their life swimming in freshwater with not many minerals and you dump them into a salty tank full of minerals?

That will stress your guppies way too much. They’ll die of kidney failure because their kidneys won’t be able to filter out all those minerals.

You have two options if you want to switch your guppies to a saltwater tank.

Add Salt to Their Freshwater Tank

The best option for moving guppies to a freshwater tank is to simply add salt to their tank.

You can’t add table salt to the tank, though. It’s not the right type of salt.

You need to add aquarium salt to the tank. And do not add too much to the tank at once. A tablespoon of salt per 10 gallons per week.

Of course, if you have any iron or stainless steel components in your tank, then do not add salt to the tank because that will rust within a few weeks (iron longer for stainless steel).

It’s really that simple to acclimatize your guppies to saltwater. It only takes two or three weeks to get your guppies used to saltwater.

In fact, you should be adding some salt to your guppy tank. These are a brackish water fish.

Transfer Guppy Fry to Saltwater Tank

The other method for having guppies in a saltwater tank is to transfer guppy fry to your saltwater tank.

They have not fully acclimatized to the freshwater, so they can quickly adjust to the salt.

I recommend doing this when the guppy fry are small. Ideally, they should be one day old when you transfer them to your saltwater tank.

It’s still not the best method, though. You will lose some guppy fry if you transfer them to a saltwater tank directly from a freshwater tank.

The fish aren’t fully acclimatized to freshwater, but they are also small and susceptible to stress.

How Much Salt Can Guppies Withstand?

Guppies can withstand water 150% saltier than seawater.

You should not have any problem having guppies in a saltwater tank. Everything else would die of kidney failure before you guppies died.


Well, that covers it for how to add guppies to a saltwater tank. It’s easy – simply acclimate them to salt and add them to the saltwater tank.

It’s their natural habitat, so they will probably enjoy saltwater a little more than they would enjoy freshwater. Plus, the pretty colors would look great in a saltwater reef tank.

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