In what kind of water do crayfish live?

Do you know what kind of water crayfish like to live in? Turns out, there is a big difference between salt and fresh water when it comes to these little crustaceans!

In this blog post, we will discuss the different types of water and what effect they have on crayfish. Stay tuned for more information about these fascinating creatures!

Whereas crayfish (aka crawdads) do well in most types of freshwater, they are not found in seawater due to the higher salt concentrations. The majority of crayfish species like freshwater with less than 1.5% salt that is chilly, hard, slightly alkaline, and well-aerated.

Crayfish are freshwater crustaceans that resemble miniature lobsters in appearance and behavior (to which they are related, but do not share habitat). They may be found in a variety of habitats such as streams, lakes, and ponds, as well as marshes, but are never found in the ocean.  

The average mature crayfish is around 7.5 cm (3 inches) in length. There are a few exceptions to this rule. A few species such as the Red Swamp crayfish of Louisiana dwell in brackish or saltwater, but the vast majority of them are purely freshwater creatures.

The water quality in which crayfish are kept matters a lot for their expected life span. A well-cared-for crayfish will typically live for two to three years, with certain species living for far longer periods of time.

Furthermore, they are often found in muddy waters at relatively low temperatures, but there are tropical crayfish able to thrive at higher temperatures.

Can crayfish live in saltwater?

The highest salinity chronically tolerated by crayfish is around 2%, but some may tolerate up to 3.5% for shorter periods of time.

Despite the fact that certain crayfish species may be found in brackish waters of up to 2% salinity, this does not imply that they would thrive in a fully marine environment at 3.5% salt or 35 ppt (parts per thousand).

One of the most salt-tolerant of crayfish is the Red Swamp crayfish (also known as Louisiana crayfish or Procambarus clarkia) that lives in brackish waters and can easily tolerate up to a 2% salt concentration, but die prematurely in the 3.5% (35 ppt) salt of seawater.  

Other more strictly freshwater crayfish can only survive for extended periods of time (up to 80 days) at maximum a 1.8% salt concentration.  

The Red Swamp Crayfish in a Louisiana swamp.

While crayfish are able to tolerate some changes in water salinity, they cannot live in seawater that is too salty. In saltwater, the osmotic balance of the cells of the crayfish is disrupted and the cells will quickly start to lose water, effectively “drying” the crayfish to death.

Putting a crayfish in water with high salt, but not having enough salt to kill it, will make it difficult for the crayfish to regulate osmosis, get rid of waste products, and will eventually lead to cellular and organ damage.

In freshwater, on the other hand, because crayfish are optimized for low salt conditions, crayfish are able to keep their salt balance, reabsorb nutrients from their blood and excrete toxins in an optimal manner when minimal salt is present.

Are there any saltwater crayfish?

There are no crayfish living in seawater, but sometimes crayfish are confused with their lobster cousins that do tolerate the saltwater conditions of seawater. One such smaller lobster is the Spiny lobster.

The spiny lobster is sometimes referred to as crawfish or crayfish, especially in England and Ireland, but they are not crayfish in a taxonomical sense.

Spiny lobsters and crayfish are often confused with one another, which is understandable. They feature two gigantic front claws, a sturdy exoskeleton, and eight legs, are both able to regenerate lost limbs, and they seem to be quite identical to one another in appearance.

Crayfish, on the other hand, are much smaller in size, ranging from two to six inches in length. Most lobsters, however, are typically at least eight inches in length when caught for food, although they may grow to be 20 inches or more in length if left alone to mature.

Crayfish vs. spiny lobster
The Spiny lobster looks similar to crayfish, but there are differences in color, claws, and, most importantly, its habitat.

When a small lobster and a crayfish are put next to one another, it may be difficult for the average person to tell the difference between the two. However, there are ways to distinguish crayfish and lobsters – the easiest of course being the water they originate from!

The most notable difference between lobsters and crayfish is that lobsters dwell in saltwater habitats such as oceans and seas, while crayfish live in freshwater areas such as lakes, rivers, streams, and ponds.

Other differences are more subtle, but those lobsters that have claws do tend to have larger claws, also relative to their body size, and stronger colors – and are usually red, whereas crayfish are more commonly brown.

Some of the key differences between lobsters and crayfish. Adapted from pediaa.com.

However, within their own streams, lobsters and crayfish seek habitats that are similar to their own, preferring to live on the bottom and hide beneath rocks and in crevices rather than on the surface of the water.

Can crayfish change from salt water to fresh water?

Generally, species that are used to saltwater have a much easier time (temporarily) tolerating freshwater than do freshwater creatures tolerate saltwater. One example is the salmon that is born in freshwater but lives most of its life in saltwater, just to seek out freshwaters again for spawning.

Most crayfish, however, are more fully adapted to freshwater and do not enter saltwater readily. A few species such as the Red Swamp crayfish do however have the ability to switch between low salt waters and freshwaters.

Not surprisingly, the age of the crayfish and whether they are given time to slowly adapt to higher salt concentrations does matter for their salt tolerance.

For example, baby crayfish born in saltwater will succumb much more quickly than an adult transferred slowly through different tanks of increasing salt concentrations.

Can crayfish live in tap water?

You may use tap water, but you must leave it to rest for at least 24 hours to enable the crawfish to acclimate to the temperature of the room and other environmental conditions before serving.

However, you need to make sure that the chlorine and fluoride content of your water supply is not too high as it can lead to toxicity in crayfish.

A good rule of thumb is that if you can drink it, crayfish can also survive in it.

When receiving new crayfish for your fish tank, acclimatize them first in a separate container. Add small pebbles or stones to the bottom of the tank to provide a little hiding spot for the crawfish, which are known for their need to hide.

How can tap water kill crayfish?

Tap water is generally ok for crayfish and they tolerate it well, however, there may be special situations you should be aware of when using you tap water for crayfish.

Especially in the case of water pipes that are less than twenty years old or if extensive plumbing repairs have just been conducted, tap water may include metal ions that are toxic to crayfish and other aquatic life.

It is probable that you may have to use water from a different source, such as bottled water, in this situation.

Crayfish like water with a pH of 7 or slightly higher (7.5 – 8.5). The water temperature should be maintained between 70 and 75 degrees Fahrenheit (21 and 24 degrees Celsius).

As tap water is usually closer to a pH of 7, you may want to measure it and increase it a bit using alkaline materials.

Consider using broken corals, dolomite filters, or decorative limestone in your aquarium to condition purified water in an ecologically beneficial way while saving money on aquarium supplies. Any of these procedures will result in an increase in pH levels.

In the case of aquatic plants, the same may be stated, but plants naturally lower pH of the water by excreting CO2 as part of photosynthesis. To lower pH levels further in your aquarium naturally, you may do it by adding more plants, some natural decorative driftwood or by infusing CO2 into the aquarium.

Can Crayfish Live in Polluted or Dirty Water?

Crayfish are very hardy organisms, able to survive a wide range of water temperatures and salinities without succumbing. The drying up and vanishing of their streams and ponds hasn’t deterred them in the least, but recent research suggests that human pollution might get to them!

They adapt to these drastic changes in their environment by hibernating in burrows or other safe havens or relocating to water sources that have not been harmed.

However, in their natural environment, crayfish may be vulnerable to pollution and other types of human-caused contamination.

Crayfish on land
Crayfish will try to migrate away from polluted water sources if possible.

As a result, a healthy crayfish population is a reliable predictor of the health of the surrounding environment. Crayfish are more frequent in streams with acidic water than in other types of streams, although they don’t thrive at too low pH levels.

However, it is possible that this abundance might be attributed to a decrease in the number of fish that feed on crayfish as a result of the acid rather than a direct, positive influence of the acid on the crayfish themselves.

There are many different kinds of crayfish that are sensitive to water pollution but crayfish species such as common crayfish (Cambarus bartonii) may be used as biological monitors to predict present and previous water quality conditions according to Alikahn et al.

Sudden mortality of freshwater crayfish implies the presence of hazardous chemicals or other types of water contamination.

Can Crayfish Live in Cold Water?

Temperatures of between 65 and 77 degrees Fahrenheit (18 and 25 degrees Celsius) are ideal for most species from the continental United States, but some may survive in a much wider temperature range.

Some species need warm water, whilst others require cold water. Generally speaking, they are entirely aquatic, yet they may survive outside of the water as long as their gills remain wet.

 While some species hibernate throughout the winter months, crayfish do not do so during the winter months.

Even though crayfishes are seldom observed in a stream during the coldest winters, they may be found in large numbers along the sides of streams, in natural crevices, and in burrows that they have dug or that they have discovered.

Can crayfish live in warm water?

Whereas the temperatures of between 65 and 77 degrees Fahrenheit are ideal for most species from the continental United States, some may survive in much higher temperatures up to 95 degrees Fahrenheit.

While most crayfish like cold water, others prefer warm water in tropical climates. Before purchasing a crayfish, a crayfish owner should do research to determine the specific needs of the crayfish species.

Crayfish from the tropics

Crayfish are an important part of the food web in tropical ecosystems, and as decomposers, they play a critical role in nutrient cycling.

Crayfish that live in the tropics can adapt to a wide range of water conditions, including salt and fresh water. Some crayfish species have even been found living in brackish water, which is a mix of salt and fresh water.

Crayfish that live in the tropics are typically smaller than those that live in other parts of the world, but they are just as aggressive and territorial. They also have more colorful shells that can be quite striking against the green backdrop of their tropical habitat.

Examples of crayfish that can live in warmer tropical waters are:

  • Red swamp crayfish (Procambarus clarkii)
  • White river crayfish (Procambarus acutus)
  • Slough crayfish (Procambarus fallax)
  • Blue crayfish (Procambarus alleni)
  • Dwarf orange crayfish (Cambarellus patzcuarensis)
  • Common yabby (Cherax destructor)
  • Tasmanian giant freshwater crayfish (Astacopsis gouldi)
  • Australian red claw crayfish (Cherax quadricarinatus)

The last one on the list is a particularly interesting one. There is just one place on Earth where you can find a red claw crayfish, and that is in northeastern Australia.

Given the intense physical conditions of its environment, this species has evolved a robust character with a wide range of climatic tolerability, which is advantageous.

It thrives at a temperature range of 23 C to 31 C and will die if the temperature rises above 36C The reproduction will only take place if the water temperature remains over 23 degrees Celsius.

See more interesting crayfish and a summary of what conditions they need to thrive in this video.

If you are more interested in the curious physiology of crustaceans, don’t miss out on my posts about how octopisquids, and crayfish breathe under (and above) water or how crayfish, crabs and lobsters regenerate their lost limbs!