Are Guppies Freshwater or Saltwater?

Most guppy keepers think guppies are freshwater fish since everybody seems to keep them in freshwater tanks. However, their natural habitat is brackish water (a combination of freshwater and saltwater).

But can they live and thrive in saltwater?

Today, we will discuss guppies’ adaptability, whether they can live in salt water, and what to do to accommodate them to their new habitat.

Can Guppies Live in Saltwater?

Guppies can adapt to any environment, in terms of water salinity, thriving in environments with salinity up to 150% of seawater. This doesn’t mean that guppies can change their habitats at will. You should never move your guppies from one habitat to another without having them undergo a gradual acclimation process first.

Despite being hard and adaptable, guppies cannot tolerate sudden environmental changes, be it temperature, salinity, pH, or other parameters. Abrupt environmental fluctuations will affect their immune system, leaving them vulnerable to bacterial infections, diseases, and parasites.

How to Acclimatize Guppies to Saltwater?

While guppies can survive and even thrive in saltwater, it’s the environmental change that can hurt them. The goal is to gradually help your guppies accommodate their new environment to minimize the shock.

To achieve that, you need to undergo several critical steps. These include:

– Preparing the Tanks

You need 2 tanks for the job. One should contain the guppies’ original water, the one they’ve been sitting in up to that point. You will position this tank lower than the second one, which will contain the saltwater.

The goal here isn’t to move guppies into a saltwater tank but to gradually pour salt water into their original tank, changing their own water’s salinity.

Make sure every guppy has at least 2 gallons of water available to ensure their comfort during the process. If you can’t use the guppies’ main tank, move them into a different container with their own tank water.

– Preparing a Tube and a Valve

You will use the tube to transfer salt water into the guppy’s container and use the valve to control the flow. This is important since abrupt changes in water salinity will dehydrate and shock the fish, potentially killing them in the process.

The valve is a must-have addition since it allows you to control the water flow to a drop, minimizing your guppies’ discomfort during the transition. If you don’t have an air pump tube, you can get one as an accessory to your air pump from Amazon or other websites specializing in tank accessories.

– Begin the Water Transfer

You will now use the tube and the valve to transfer the water from the saltwater container to the guppies’ habitat. The saltwater tank should be positioned at least 6 inches above the guppies’ container to ensure ease of flow.

Regarding the flow rate, you should only allow 1 drop per second. This is slow and will take time, but it’s necessary to prevent your guppies from experiencing a too abrupt change in salinity levels.

I suggest removing some of the guppies’ water before starting the transition. You should remove around 25% of the water and replace it with saltwater via the tubing. When the water reaches its initial level, empty 75% of the water and redo the process, this time speeding up the flow rate a bit. You can even empty more of the water, until you only have 1 inch left. The flow rate can now increase to 2-3-4 drops of saltwater per second. Your guppies are already accustomed to their environment.

Let the tank fill up and monitor your guppies for at least 30 minutes to see how they behave. If you see no concerning signs like visible agitation, erratic swimming or gasping for air, you can safely conclude that your guppies have accommodated to a saltwater environment.

– Move Guppies into the Main Tank

You can now safely move guppies into their main saltwater tank, but do it carefully. They have spent quite some time into the transition container with less water than their main environment. This means that the tank’s temperature will be different than what they have experienced up to that point.

I suggest using a water bag when making the transition. Move the guppies into the bag and let the sealed bag float into the main tank. 30 minutes should be enough for the temperatures to equalize, allowing for a safe transition.

Another critical aspect to mention – verify the salinity levels of both the main tank and the transition container. You need to make sure that the main tank doesn’t have a higher salinity level than what guppies have accommodated to.

And, since we’re at this point, you should monitor your guppies over a period of at least 24 hours. If your guppies haven’t fully acclimated to their environment, they might begin experiencing dehydration, but the symptoms will be delayed.

If they show no concerning symptoms of gasping for air, wobbling, or swimming near the water’s surface, everything’s fine.

How Much is Too Much Salt for Guppies?

Guppies are highly adaptable creatures that can withstand a variety of environments, from clean, fresh water to full marine habitats. The only thing they’re not good at is abrupt environmental changes. Your guppies should be fine with marine-level habitats so long as you ensure a smooth and gradual transition.

I suggest monitoring salt levels in the main tank so you can have a reference point compared to marine environments. That being said, you can have excessive salt, beyond which no fish can survive. But this shouldn’t be a problem so long as you inform yourself on the subject and don’t go overboard with it.

Can Guppies Live in a Reef Tank?

I wouldn’t advise keeping guppies in a reef tank for several reasons. One of them is the fact that a reef tank requires a most stable water chemistry compared to fish-only environments. Any increases in ammonia and nitrate levels will hurt the corals.

Then, corals need more turbulent waters with stronger currents than what guppies are used to. And as a 3rd point, reef tanks require more intense lighting.

These factors make guppies unfit for living in such an environment. They may be able to adapt, but with great difficulties, and they won’t experience the same level of comfort as with their own tank.

You can choose many fish species for your reef tank if you’re thinking about setting one. These include Azure Damselfish, McCosker’s Wrasse, Midas Blenny, Watchman Goby, and many others.


Guppies generally prefer brackish water, but they can adapt to pretty much any environment given the opportunity. The key factor here is gradual transition. Allow your guppies time to adapt to the new environment gradually, and they will.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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