Crayfish are among the most underrated freshwater pets. These small crustaceans have distinctive personalities, ranging from adventurous tank explorers to meek cave hiders. While crayfish make great pets for beginner aquarists, here’s something to keep in mind: despite their charming, smaller lobster-like appearance, they will fight over pretty much anything. Over what, you may ask? It depends.
Understanding the reasons why crayfish fight can offer some perspective if you notice your specimens bullying each other. Some causes include competition over mates, a lack of food, or a small aquarium.
1. Your Crayfish May Feel Cramped
Despite measuring three inches long, crayfish need plenty of space. While having 10 gallons per specimen is a good start, you want a sizeable tank with generous gallonage and a spacious, horizontal base. After all, crayfish are bottom-feeders and won’t swim around the aquarium like finned fish. If your crayfish feel confined, this will increase their stress levels and lead to fights over territory. To completely eliminate or reduce the risk of fighting among your crawfish, invest in a bigger tank. Be sure to include live plants and other aquarium decorations, like caves and hidey holes, to add enrichment.
2. Your Crayfish Have Conflicting Personalities
Every crayfish is its own individual. Some are “alpha” crawfish—ruthless, extremely competitive specimens that have no problem throwing their weight around (all 30 grams) to get their way. Others are more docile and can peacefully co-exist with other crayfish. There’s no predicting the temperaments of crayfish upon purchase, so there’s no surefire way to tell whether multiple crayfish have compatible personalities.
If you want to have multiple crawfish, you may consider getting one, studying its temperament, and then deciding whether you want to add another. How do you assess a crawfish’s temperament, you ask? Observe whether it chases other fish, attacks other crustaceans, or appears defensive when tankmates approach its part of the tank. Your findings may inform whether you want to add another crayfish—or not.
3. There’s Not Enough Food
Crawfish are scavengers, meaning they’ll eat whatever decomposing matter falls to the bottom of the tank. So, if you keep crawfish with a top-dwelling fish species (like guppies and hatchet fish), they will eat anything they don’t. This helps to keep your aquarium clean while also preventing decomposing organic matter from throwing off the aquarium’s water parameters.
If you keep multiple crayfish, and they suddenly start fighting, you should consider whether everybody’s getting enough food. Consider dropping a few frozen peas into the aquarium and see whether this resolves any fighting. If not, you should consider separating the crayfish. You could also let them sort things out—but you might have one less crayfish when it’s said and done!
4. A Crawfish Has Just Molted
As a crayfish grows, it will shed its hard exoskeleton. During this period, a crawfish is very vulnerable, as this process takes a lot of energy, and their new exoskeleton isn’t immediately hard. Crawfish are intelligent creatures that can recognize weaknesses in their tankmates and may view a molting crawfish as an easy target. If you’re concerned about a molting or newly molted crawfish being attacked, you may place it in a separate quarantine tank until you feel confident about reintroducing it to the main aquarium. Alternatively, you could temporarily remove the non-molting, possibly opportunistic crawfish.
5. They’re Competing for Mates
If you keep multiple crayfish in a large aquarium, they may have peacefully co-existed until mating season rolled around. Mating season occurs when temperatures drop and the water cools to about 50 degrees Fahrenheit. Here, competing males will rely on their powerful claws to bully, injure, and even kill one another. The good news is that it’s relatively easy to sex crayfish and separate males and females. For example:
- Male crayfish are generally lighter in color because they molt twice a year, as opposed to darker females, which molt once a year.
- Males have larger claws.
- Females have larger bodies––necessary for carrying eggs.
You may consider getting a back-up aquarium to keep males and females separate during mating season. You may even decide to keep sexes separate altogether to reduce the risk of infighting and competition for females.
6. They Need More Hiding Spots
Crayfish may “throw claws” if there aren’t enough hiding spots to go around. It’s possible to keep multiple crayfish in a harmonious environment if they have logs, rocks, and caves to call their own. These crustaceans love claiming certain areas because it helps them feel secure when they molt, which temporarily opens them to attacks from rivals. If you’re on a budget, you can get creative with DIY hiding spots for your crayfish. For instance, you could use the bottom of a broken clay pot to create a mini cave. You could also use an empty mason jar and partially bury it in the aquarium’s substrate.
Tips for Caring for Pet Crayfish
Crayfish make excellent pets for first-time and experienced aquarists alike. However, as with any pet, some research is needed beforehand to ensure a peaceful aquatic environment. Some fast tips include:
- It doesn’t take much to put a crayfish in a fighting mood. If you want to keep them with other fish, you should select top-dwelling species, including betta fish, danio, and killifish. Avoid bottom-feeders; they could become quick meals!
- Add some eggshells to your aquarium when your crayfish molt. They’ll feed on the shells and gain some much-needed extra calcium.
One last thing! Note that if you purchase crayfish online (yes, you can buy them on Amazon), you may get more than you bargained for. For example, if you purchase a 12-pack of crayfish, you may just find yourself with 15! Some aquarium companies intentionally send more specimens in case some die in transit. Needless to say, if you’re going to keep multiple crayfish, you’ll need a sizeable tank.
