If you are a new crayfish keeper or thinking about keeping crayfish, wondering about how large they can get is normal. The fully matured size of a crayfish will vary largely from captivity to wild.
On average in captivity, crayfish grows up to 3-4 inches when fully matured. Electric blue crayfish can get up to 6 inches in captivity. In wild, crayfishes are generally 6-7 inches long. Some giant crayfish species (Tasmanian) can get up to 31 inches.
The size of a crayfish depends on many factors, mainly if it is captive bred or from the wild. Also, the diet, habitat, etc. play an important role on the overall size of the crayfish. I’ll get into details in the rest of the article.
How Big Do Crayfish Get In Captivity?
The exact size of the crayfish will depend on its species. As I have said, normally crayfishes get up to 3-4 inches in captivity. However, the blue electric species can grow up to 6 inches!
In the table below, I am mentioning the fully matured size of different pet crayfish species. Keep in mind that these sizes are an average estimation and can vary from your personal experience. This is because, the size of a crayfish in captivity will vary depending on how it is kept and fed.
| Crayfish Species | Fully Matured Size |
|---|---|
| Australian Crayfish (Cherax destructor) | 8 inches |
| Lousiana Crayfish (Preocambarus clarkia) | 6 inches |
| Florida Lobster (Procambarus alleni) | 2.5 inches |
| Red Claw (Cherax quadricarinatus) | 8.5 inches |
| Orange Dwarf Crayfish (Cambarellus patzcuarensis) aka CPO | 1.6 inches |
| Miami Cave Crayfish (Procambarus milleri) | 3 inches |
| Blue Brazos Crayfish (Cambarellus texanus) | 2 inches |
How Big Do Crayfish Get In Wild?
The size of crayfish in the wild also varies from species to species. Generally, they get up to 6-7 inches. However, some of the species (Cherax sp.) can get up to 12 inches.
Till now, the largest crayfish species found is the Tasmanian Giant Freshwater Crayfish (Astacopsis gouldi). Here is a short profile of this largest freshwater crayfish species:
| Size | 30-31 inches |
| Weight | up to 13 lb (6 kilograms) |
| Lifespan | can survive up to 60 years |
| Habitat | rivers below 400 meters depth around Tasmania |
How Long Does A Crayfish Need To Get To Full Size?
Generally, a crayfish reaches sexual maturity in about 3-4 months. Around this time they reach the fully matured size.
However, this time frame will vary largely depending on the species and some other factors. In case of Tasmanian giant crayfish species, they’ll reach sexual maturity much later as they can live up to 60 years!
Some of the pet crayfish species (Cherax Sp.) can also take a bit of a longer time to reach its full potential size.
Crayfish Growth Factors
The size of a crayfish in captivity will also depend on how its kept and fed. If the crayfish gets its proper habitat and feeding, it will surely reach the maximum potential size.
The most important growth factors for crayfish are habitat, feeding and water parameters. I’ll talk about each of them in details.
If you ensure these 3 factors are fulfilled properly, then your crayfish will live a happy life with its maximum size!
Habitat
Tank Size
When talking about habitat, the first thing we need to address is the tank size. If you want your crayfish to reach its maximum size, you need to provide it with enough swimming and exploring space.
Most crayfish keepers recommend a 5 gallon tank for any dwarf crayfish species. However, I think 5 gallon is not enough and you need to keep crayfish at least in a 10 gallon tank.
Larger tank is also very forgiving. So, it is better for beginners to start with a large tank than a 5 gallon.
However, if you are keeping freshwater lobsters/larger crayfish species (Cherax Sp.), you should get at least a 30 gallon tank for their larger size.
Hiding Space
Crayfishes need lots of hiding space in their habitat. Specially if you are keeping multiple crayfish together, then hiding places are must.
Crayfishes are generally very territorial animal. So, they can easily fight with each other to win territory. That’s why, when keeping more than one crayfish, a larger tank with lots of hiding spaces is widely recommended.
Creating hiding spaces in the habitat is very simple. You may not need to spend anything extra if you are creating enough. Here are some of my hiding ideas. You can try out your own ideas too!
- Get some pieces of rocks and form a cave shape inside the tank. This will also look naturalistic & pleasing! When forming the rocks into a cave shape, you can use aquarium safe glue. This will ensure the rocks won’t collapse and cause any potential danger to your crayfish.
- Get some PVC pipes, cut them into smaller chunks, and leave them in the tank. The crayfish will use these pipes as hideout comfortably.
- You can use large driftwoods as some type of hiding spot. However, be sure to treat the driftwood properly before placing it inside the tank.
- Some of you may think of planting real plants to create hiding spaces. This is NOT recommended at all. Crayfish loves to eat aquatic plants. If you want to keep your crayfish in a planted tank, it will tear up the plants into species within a matter of days. So, real plants are not an option!
Feeding
Feeding crayfish is the easiest thing to do! They can eat anything you offer. From soft plants to pellets, blanched vegetables, etc. everything is safe for crayfish to eat.
I’ve written a detailed guide on crayfish feeding. You’ll learn everything you need to know about feeding crayfish from that guide. Don’t forget to check it out!
However, if you want your crayfish to reach its maximum size, you do need to provide it with proper & balanced nutrition. For this, you can choose any reputable commercial food. Some of the options can be:
- Algae wafers
- Sinking pellets
- Spirulina flakes
- Shrimp food (i.e. Bacter AE) etc.
You can feed only one type of commercial food. However, I like to mix 2 or 3 of them up to bring a change to the diet. Like any other inhabitants, crayfish can get bored to only one type of food. So, it is better if you can mix them up.
Also, feed your crayfish blanched vegetable. This is excellent for nutrition as well as bringing a change to the diet. Some good options can be:
- Spinach
- Zucchini
- Carrots
- Peas etc.
Do not feed your crayfish anything that contains copper. Though copper can be a nutrient for crayfish, excessive copper is deadly for them. So, it is better to discard copper completely from the diet.
Water Parameters
Generally, crayfishes can withstand a large range of water parameters as they are pretty hardy inhabitants. However, if you want your crayfishes to reach the maximum size, you do need to provide them the correct water parameter ranges. Also, pristine water quality is important for crayfish!
Here is the ideal water parameter ranges for keeping crayfish:
| Water Parameter | Ideal Range |
|---|---|
| Ammonia, Nitrite, Nitrate | Close to 0 ppm |
| Temperature | 65 to 80 Degrees Fahrenheit (19 to 27 degrees Celcius) |
| pH | 6.5 to 7.5 |
| GH | 4-10 ppm |
| KH | 3-10 ppm |
| TDS | 100-300 ppm |
| Important Note | Consistent water parameters are more important than trying to hit the correct number. If your tank water pH is 8.0, it’s not the end of the world for crayfish. Just make sure the parameters are consistent and do not change rapidly. |
Water parameters can be a very confusing topic for beginners. If you are still confused, read my water parameters guide for crayfish. I’ve explained everything you need to know there.
Biggest Crayfish Ever Caught!
It was November 2017. A group of people was surveying the nearby sites of Tarkine forests, rivers, and plains. In a nearby rainforest of North-West Tasmania, a giant crayfish was discovered.
It weighted about 3 Kilograms. According to crayfish expert & researcher Todd Walsh, this was his second largest crayfish catch!
The crayfish only had one full-sized claw. If it had two claws, the weight would have been close to 5 Kilograms!
