Can Guppies Live in Saltwater?

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Guppies are tropical fish that typically live in fresh and brackish water. For those who are unfamiliar with the term, brackish water is the middle ground between freshwater and saltwater. It essentially has a higher salt content than freshwater but not enough to qualify as a genuine saltwater environment.

People tend to associate guppies with freshwater environments-only because that’s how most aquarium keepers grow them. However, guppies are a very resilient and adaptable species, capable of inhabiting a multitude of environments. Naturally, so long as they don’t exceed their ideal living parameters by much.

So, yes, you can keep guppies in saltwater. The only question here is how salt can the water be?

Today’s article aims to investigate guppies’ adaptability to saltwater and teach you something new about this already amazing fish species.

Are Guppies Freshwater or Saltwater Fish?

Most guppy species prefer freshwater environments, as well as brackish water habitats. They can live just fine in either of these settings, so long as they meet their ideal living parameters. These include oxygenation, temperature, available food, water movement, and currents, etc.

This means that guppies can adapt to a variety of aquatic environments with varying degrees of salinity. But how salty can the water get before guppies start to feel uncomfortable? And, most importantly, how can you help guppies accommodate to a saltier environment with minimal discomfort?

How Long Can Guppies Live In Saltwater?

The answer depends on how we define saltwater. Different aquatic environments can come with varying salinity levels, and guppies cannot inhabit all of them. Guppies can generally tolerate up to 58.5% salinity. Anything above that will increase their level of discomfort gradually and usually fast.

This is also where we need to mention the acclimation period. Many guppy keepers will transition guppies from freshwater environments to more brackish ones abruptly. Guppies can fall sick and die even in environments with optimal salinity levels if the transition is too rapid.

This abrupt transition can cause guppies to experience dehydration and even death. The goal is to ensure gradual transition, allowing guppies the time to accommodate to their environment.

How To Acclimate Guppies to Saltwater?

The acclimation process is vital for ensuring your guppies’ safety during the transition. An abrupt change of environment can hurt your guppies and even kill them, despite the salinity levels being within the safe parameters.

There are 7 primary steps to follow to provide your guppies with a safe transition between fresh and saltwater environments:

– Choosing the Right Tank

Avoid metal frames since these can oxidate in water with higher salt content, which can poison the water. Choose a glass-only tank and make sure it’s of the ideal size for your guppy population.

Typically, every guppy should have at least 2 gallons of water available. I would suggest getting even more than that since you also need to account for aquarium decorations and plants.

– Ensure Flowing Water Currents

An air pump is a must since guppies need moderate water streams to remain healthy and thriving. Stagnant waters will hurt them. Water currents improve oxygenation and allow guppies to breathe better, diminishing their stress related to any environmental changes.

In short, getting an air pump will ease your guppies’ transition towards a more brackish environment. Just make sure to settle the power to a bearable level since guppies like currents are not too powerful.

– Set the Acclimatization Tank

The acclimatization tank should ideally contain the water that the guppies were already living in. This will minimize their stress during the transition and reduce the risks of adverse reactions.

After doing that, you need to:

  • Empty some of the water from the aquarium the guppies live in (30% to 50% should do)
  • Fill up another tank with saltwater (the salinity concentration should be no higher than 58.5%)
  • Place the saltwater tank next to that of guppies’, but on a higher plane
  • Use a tube and a valve to move water from the saltwater tank to the guppy tank

– Control the Flow Rate

You need to ensure a slow and steady flow rate since moving too much saltwater into the guppies’ environment can hurt them. The valve will allow you to set the flow rate to 1 drop per second or 1 drop every 2 seconds. It sounds like a slow process, and it is one, but it also makes for a safer approach.

– Fill Up The Tank

The valve should function until the water in the guppies’ tank fills up to its previous levels. When that happens, you will officially have brackish water.

At this point, you should watch your guppies’ behavior closely. If everything is fine, they shouldn’t show any signs of stress. If they do, you’ve probably added too much salt too fast.

In that case, you should have another tank ready where you can move guppies and repeat the process. This time with less salt.

Two points to remember here:

  1. Try to get the right salt concentration the first time. Moving guppies from one tank to another usually stresses them out unnecessarily.
  2. Make sure you move then in a cycled tank with optimal environmental conditions to prevent any unwanted surprises
  3. Repeat the Process

You need to repeat the process once the tank is full, resulting in a brackish water environment. Empty around 70% of the water and start all over again.

This time, you can boost the valve’s flow rate to 3-4 drops per second since your guppies have already adapted to brackish conditions.

– Relocate the Guppies

Once the guppies seem comfortable in their now brackish environment, it’s safe to move them to the saltwater tank. Just make sure that the saltwater tank meets the same parameters as the acclimatization tank. This includes oxygenation and temperature.

Any significant variations in these parameters will make your guppies uncomfortable, stressed, and even potentially hurt them.

How Much Salt Can Guppies Tolerate?

Guppies can tolerate, on average, salinity levels of up to 58.5%. Anything higher than that can hurt them. That’s because guppies aren’t saltwater fish, as their natural environment varies between freshwater and brackish.

With that in mind, you should not keep guppies in saltwater since that’s far from ideal for them. Always verify salinity levels before moving the guppies into a saltwater tank to make sure they remain stable and optimal.

Can Guppies Live in a Marine Tank?

Yes, they can. Evidence suggests that guppies can live in waters with up to 150% of the salt level of seawater. Guppies’ high adaptability allows them to adapt to a multitude of environments, including saltwater ones.

Just make sure you help their transition by following the steps I’ve pointed out.


Guppies are hardy and adaptable fish and can thrive in a variety of environments. They can also live in saltwater, provided you help them transition safely.

If interested in transitioning your guppies towards a saltwater tank, check the 7 steps I’ve provided or comment below for additional support.

Updated: November 21, 2021
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