Today I would like to talk about the smallest known crayfish species in the world, with adults rarely reaching 2.5 cm (1 inch) total length. Cambarellus diminutus absolutely gorgeous and beautiful crayfish can be a great addition to any aquarium or paludarium setup.
They are the most peaceful crayfish species you can ever find; they are also relatively hardy and very easy to care for. In addition, Cambarellus diminutus can breed in captivity!
The only problem is that Cambarellus diminutus is very rare in the pet trade. In addition, there is so little information on this species that it was even listed as in need of conservation attention for listing under the Endangered Species Act and is listed as Data Deficient on the IUCN Red List.
In this care guide, I will share with you everything I found and know about Cambarellus diminutus species including their behavior, life span, growth, feeding, handling, embryonic development, and etc.
Quick Notes about Cambarellus Diminutus
| Name | Cambarellus diminutus |
| Common Names | The Smallest crayfish |
| Scientific Name | Cambarellus diminutus |
| Tank size (optimal) | 10 gallons (~40 liters) |
| Keeping | Easy |
| Breeding | Easy. |
| Size | up to 2.5 cm (~ 1 inch) |
| Optimal Temperature | 22 – 28°C (~72°F – 82°F) |
| Optimal PH | 5.5 – 7.0 |
| Optimal GH | 3 – 12 |
| Optimal KH | 1 – 6 |
| Nitrate | Less than 20 ppm |
| Diet | Detritivore / omnivore |
| Temperament | Conditionally Peaceful |
| Life span | up to 2 years |
| Color Form | Grey/reddish to dark grey |
Cambarellus Diminutus other Dwarf Species of Crayfish
According to some studies, there are 19 species belonging to the genus Cambarellinae.
They are all pretty small and may look quite similar. So, differentiating them is almost impossible unless you are a professional biologist. For example, Cambarellus diminutus closely resembles Cambarellus schmitti, but differs in possessing considerably reduced elements on the processes of the first pleopods.
Of course, some people may disagree and say that there is an easier way and these species have different coloration and/or color patterns, for example:
1. Cambarellus ninae – brown-colored,
2. Cambarellus montezumae – yellow-colored,
3. Cambarellus patzcuarensis – orange-colored,
4. Cambarellus shufeldtii – grey/reddish to brown-colored.
5. Cambarellus texanus – olive to brown-colored.
6. Cambarellus puer – orange-red to light brown.
The only problem is that this method of “classification” is not accurate and, in some cases, it is totally compromised. Why?
Because these species of dwarf crayfish can crossbreed creating some new color variations and patterns. In addition, the color can vary even within the same species. The diet can also affect coloration. We also have a culling (selection).
As a result, it makes really hard to find out what kind of species we might have in the tank.
Origins, Natural Habitat of Cambarellus Diminutus
Cambarellus diminutus has a very restricted range (water bodies within an approximate 3260 km2 area) along the Gulf Coastal Plain of southeastern Mississippi and southwestern Alabama.
In nature, this species occurs in ditches as well as pools within sluggish streams where water was slow-moving and heavily vegetated.
Cambarellus Diminutus Description
As I have already said, Cambarellus diminutus is the smaller crayfish in the world. In most cases, they will grow up to 1.5 – 2 cm (0.6 – 0.8 inches). Even though there are reports that some individuals reached almost 3 cm (slightly more than 1 inch), it does not happen often.
In pet stores, Cambarellus diminutus are also available in bright blue colored morphs that are dramatically different from their normal, relatively drab, wild type coloration.
Wild individuals of this crayfish are mostly tan, gray, and brown. It helps them to hide from predators and avoid unnecessary attention.
Note: There is no information on who and how created the blue color morph.
This crayfish has many dots that have a lot of pattern and color variations. The abdomen has a pale olive ground color.
Cambarellus diminutus have graceful elongated and narrow shape pincers.
Under optimal conditions, the lifespan of Cambarellus diminutus is only about 1.5 – 2 years.
Cambarellus Diminutus Behavior
Cambarellus diminutus are not as aggressive as their bigger cousins (Blue crayfish, Red crayfish, Marbled crayfish, Cherax Destructor, etc.).
However, despite their tiny size, they are still not completely peaceful and inoffensive. Even though they usually do not start fighting, once they see each other, they are territorial animals (especially males) and prefer to keep a distance from their own kind.
They will pinch and claw when they feel threatened or in danger.
Cambarellus diminutus can dig at the substrates and pick tiny food particles but this species is not a burrower type of crayfish.
They are not very messy and/or destructive. They are not strong enough to constantly move stuff in the tank.
Another thing that you should remember that these crayfish are excellent escape artists and can spend some time out of the water.
Note: So, it will be a good idea to use a lid and make sure the water line in your aquarium is not too high.
They are mostly nocturnal.
Feeding Cambarellus Diminutus
Cambarellus diminutus are extremely opportunistic eaters. It means that they can eat about anything edible they come across. They will gladly spend all their time scavenging for food and wandering around the tank.
Suggested foods for your crayfish are:
- vegetables,
- seeds,
- algae wafers,
- blackworms,
- bloodworms,
- crushed snails,
- earthworms,
- brine shrimp,
- dead fish or shrimp.
Important: If you want to give them the best life, they need to have a varied diet. For example, you should avoid giving protein-rich foods all the time, even if it looks like that they can eat it none-stop.
Feed your crayfish bottom-dwelling live food along with sinking pellets of any brand (examples with links to check the price on Amazon):
- Shrimp pellets
- Shrimp Granules
- Fish food (TetraMin® flakes, etc)
- Shrimp food (Hikari’s crustacean food like Hikari Shrimp Cuisine, Algae wafers, etc )
- Frozen blood worms
Surprisingly crayfish also enjoy vegetables such as shelled peas and zucchini. You can read my article “How to Blanch Cucumbers and Zucchini for Shrimp, Snails, and Fish the Right Way.”
Supplement their diet and make sure they get enough calcium (for the exoskeleton) by regularly feeding specialized invert foods.
| I highly recommend reading my article “How to Supplement Shrimp and Snails with Calcium”. |
How often should We Change the Food?
Leave the food for 24 hours before removing it. Make sure that whatever they do not consume in one day is removed, otherwise, it will foul up the water and cause a lot of problems (such as Black bearded algae, Hydras, Planaria, etc.)
Keep in mind that Cambarellus diminutus are mostly nocturnal. So it is recommended to feed them at night (at least in the evening) so that you can replicate the conditions and environment under which they eat naturally.
How Often to Feed Cambarellus Diminutus?
Personally, I would recommend starting with 3 – 4 times a week and change it to your livestock’s requirements.
Don’t forget that they are scavengers, so when you feed your fish, shrimp, or snails, they will also get their share.
However, if they get hungry, they can try to go after the shrimp, fry, or small fish.
That is why it is absolutely important crawfish be fed enough to keep the balance in the tank.
Cambarellus Diminutus and Live Plants
In the wild, Cambarellus diminutus species occur in heavily vegetated water bodies. However, it should not worry you.
They are safe to keep with any type of live plant. This species does not eat healthy plants and can, therefore, be kept in beautifully planted aquariums. Even more, they will benefit from live plants by collecting bacteria and microorganisms from them.
Keeping and Housing Cambarellus Diminutus
Like all crayfish species, Cambarellus diminutus is very easy to care for. They are not high-maintenance pets. But if you want to have a happy and healthy crayfish as long as it is possible, it is important to give it everything it needs, including proper care.
First of all, the tank should be cycled. High ammonia and nitrates can harm them.
Tank Size:
The minimum recommended tank size for Cambarellus diminutus is a 5-gallon (20-liter) tank. Ideally, a 10-gallon tank (40 liters) will suit them perfectly.
Of course, they can live and thrive even in smaller tanks. However, in this case, you will have to be in constant control over your water parameters. Unfortunately, in small tanks, everything can go wrong very fast.
Tip: These crayfish are great escape artists. So, a tight-fitting lid is essential.
Water Parameters:
Temperature: Cambarellus diminutus can live in a wide range of temperature conditions 15 – 30 C (59 – 86 F). However, the optimal temperature in the aquarium should be in the range of 22 – 28 °C (72 – 82 °F).
They do not require a heater. Room temperature will suit them absolutely fine.
pH: According to the study, in nature, Cambarellus diminutus prefer acidic water! Unlike most crayfish species, optimal water pH should be provided for this species in the range of 5.5 – 7.0.
Hardness: They will appreciate optimal KH 1 – 6 and GH between 3 – 12 GH.
Filtration:
Personally, I would always recommend using sponge filters or matten filters for any small tank setups.
These filters are cheap, easy to maintain, and clean; they provide a lot of surface to graze on, and absolutely safe for the baby crayfish. In addition, Cambarellus diminutus will not damage and tear apart the sponge as large crayfish species often do.
However, for bigger tanks, sponge filters may not be good enough. In this case, you will need to either hang on the back or canister filters.
Tip: If you have a canister or hang on the back filter and you are planning to breed Cambarellus diminutus, the filter intake should be covered with a sponge or net. Because of the small size of the baby crayfish, they can be easily suck up.
Although, some aquarists can keep Cambarellus diminutus crayfish in the tap water, I always recommend using RO/DI water remineralized with Salty Shrimp GH+.
This way you can control your water parameters and create the optimal conditions for your pet.
Lighting
All crayfish species are nocturnal creatures. So, they could not care less about it. Lighting should be adapted to the needs of plants in your tank.
Read more about it in my article “Advanced Guide to Planted Tank Lighting”.
Substrate:
In the aquarium, Cambarellus diminutus should be provided with soil and/or sand substrates. It will be an ideal setup for them.
Note: According to the study, in nature, their substrates consist of mud and sand.
Decorations:
Hiding spots should be installed in the tank for giving them the places to hide.
There should be plenty of dark areas for them to hide in and these should be created out of stones, driftwood, PVC pipe, plastic tunnels, plants, etc.
Note: If you are planning to keep several Cambarellus diminutus, or they are going to be in a community tank, each of them needs a hiding place to feel secure in different parts of the tank! This is extremely important especially during molting.
Related article:
In addition, do not forget to acclimate them (read more about this process).
Tank Equipment (links to check the price on Amazon)
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Molting and Cambarellus Diminutus
The same as any crustaceans, Cambarellus diminutus crayfish need to shed their exoskeleton in order to grow in size and also regrow any lost limbs.
The molting process (the molt cycle) is the most important part of crayfish’s life. This process has 4 phases:
- inter-molt,
- pre-molt,
- molt,
- post-molt.
These inter-molting periods can be short (weeks) when the crayfish is young. As they age, these periods will begin to happen further and further apart. For example, adults molt every few months.
During pre-molting periods, most metabolic activities are reduced to a minimum. They stop eating and become very lethargic.
When they are in the molting process they will look for a place to hide. The reason they like to stay hidden during this process is that they are completely defenseless until their skeleton fully hardens.
So, NEVER disturb them when they are about to molt.
You can read more about it in my article Crayfish and Molting Process.
Cambarellus Diminutus Male and Female Difference
Cambarellus diminutus are sexually dimorphic. There are a few indicators that give away the gender of the animal.
- The female and male Cambarellus diminutus can be told apart by looking at the lower part of their abdomen (the lower part of the white section of the underbelly).
Males have an extra set of pleopods used for internal fertilization. Therefore, if you see that there is like a triangular-ish forming of small legs. That will indicate a male.
Females have seminal receptacle and lack the extra pleopods found behind the walking legs on males. Females do not have the same section. There will not be that triangular-ish forming of small legs. What you will see is a small nub. That will indicate a female.
- Females are a little bit bigger than males and have a wider abdomen to hold the eggs.
Related article:
Breeding Cambarellus Diminutus
Mating:
Make sure you have at least one male and one female in your tank. According to the observations, they reach maturity when they are about 2.5 – 3 months old.
If a female is interested in mating, she will allow a male to approach. After that, the male flip over the female, clamps her claws and puts her on the back, and deposits the spermatophore in a protective receptacle in the female.
The female crayfish will then fold over her tail, placing it under her body so that she may fertilize her eggs.
Interesting fact: In the crayfish world, strength does not play any role in mating. Even when the female is bigger and stronger than the male, she will let him “defeat” her and flip over. The results of the study show that, if the females are not ready to mate, they will always escape even when the males are bigger and stronger.
Eggs:
Female Cambarellus diminutus usually carry a few dozens of eggs. They use their appendages (pleopods) to keep the eggs clean from dirt and well oxygenated.
Depending on the temperature, it usually takes from 3 – 4 weeks to hatch. If you can see dark spots (developing eyes) on the eggs it means that they are about to hatch.
After hatching and separation from the mother, it is recommended to keep baby crayfish in a rearing tank to prevent potential aggression from the adults.
Cambarellus Diminutus and Fish Tankmates
Even though Cambarellus diminutus are the smallest and probably least aggressive crayfish species in the world, they are not social anyway and prefer to be by themselves in a community tank.
Fish:
No aggressive fish should be kept in the same tank with them.
They may behave aggressively towards a fish if they feel threatened. They do not have the capability to kill most fish (unless it is ill and weak), but they will not hesitate to take chunks of fins if they feel threatened.
Shrimp:
Some aquarists say that their Cambarellus diminutus and dwarf shrimp are doing just fine in their tanks. While others blamed them for the drastic reduction of the shrimp colony.
Basically, it is not possible to predict the outcome because it is going to depend on the individual.
In any case, if you are seriously planning to breed dwarf shrimp, I strongly believe that keeping them together is not the best course of action.
That is why in my guides I never recommend keeping even dwarf crayfish species with small shrimp. The only exception might be Ghost shrimp, Amano shrimp, Bamboo shrimp, and Vampire shrimp, these shrimp species can grow way bigger than Cambarellus diminutus and should be safe.
Note: Do NOT forget to keep them well-fed, it will reduce their hunting instinct.
Snails:
There should not be problems with the large snails. The problem is that they can nip off the antennae periodically.
Bad Tank Mates:
You need to avoid keeping Cambarellus diminutus with:
- Larger or aggressive fish.
- Any other crayfish species.
- Other freshwater crab species (with a few exceptions).
- Dwarf frogs.
In Conclusion
Cambarellus diminutus are low maintenance and simple to care for. They are very interesting creatures and amazing pets for keepers of any level. They can even be kept in nano tanks.
These tiny crayfish have perky personalities and make movements that are interesting to watch.
Unfortunately, the smallest crayfish species in the world is pretty rare in the crayfish pet trade.
Related article:
Tasmanian Crayfish Profile. The Largest Crayfish in the World
References:
- Status Survey for three rare Alabama crayfishes: Cambarellus diminutus, Fallicambrus burrisi, and Procambarus lagniappe. Illinois Natural History Survey. 2014
- Garden ponds as potential introduction pathway of ornamental crayfish. Knowledge and Management of Aquatic Ecosystems (2014) 414, 13. DOI: 10.1051/kmae/2014019
- Imports of ornamental crayfish: the first decade from the Czech Republic’s perspective. Knowledge and Management of Aquatic Ecosystems (2015) 416, 04. DOI: 10.1051/kmae/2014040.
- Distribution and habitat use by dwarf crayfishes (Decapoda: Cambaridae: Cambarellus). Wetlands, Vol. 16, #4 1996.