Fiddler crabs (also known as ‘calling crabs’) are small crustaceans that belong to the Ocypodidae family. Found along sea beaches and in lagoons/swamps with part-salt, part-fresh water conditions, this species makes an interesting addition to a brackish tank. But are they hardy and easy-to-care-for?
Yes, fiddler crabs are quite hardy, though they do have some specific environmental needs which must be met for them to live a healthy life in captivity. Mimicking the natural habitat of this species is the best way to promote longevity.
Now that you know fiddler crabs are fairly easy to maintain, let’s ‘dive deeper’ into the aquatic world of this tiny crustacean. We’ll discover how long they live in captivity, how big they get, what tank conditions are best, what to feed them, and if they’re prone to disease.
So, if you’re ready to learn more about this resilient and amusing little invertebrate including how to properly care for them, then let’s begin!
Are Fiddler Crabs Hard to Keep?
Fiddler crabs are considered low maintenance by aquarist standards. All they need is food, brackish water, and soft sand to bury in. They essentially take care of themselves and will feast upon algae, detritus, and decaying organic matter in an aquarium.
The longevity and health of fiddler crabs is directly linked to their surroundings. The tank parameters must be conducive to this species’ needs and should mimic their natural habitat as closely as possible. If not, fiddler crabs won’t survive their first year in captivity.
How Long do Fiddler Crabs Live?
In captivity, fiddler crabs can live up to 5 years – with the right aquatic conditions and proper care, that is. The average lifespan, however, is between 2 and 3 years. To improve their longevity, keeping the tank clean while providing adequate food and space is a must.
To keep them healthy and promote longevity, this species shouldn’t be handled unless necessary. Too much human contact not only increases stress but can also lead to injury (especially for the handler who can get pinched by a fiddler crab’s claws on account of fear).
How Big do Fiddler Crabs Get?
Fiddler crabs can reach lengths of 2 inches in adulthood. Their small size, calm temperament, and hardy nature make them a welcome addition to almost any brackish tank (with non-predatory, non-aggressive fish, that is).
Fiddler crab males and females are typically the same length with the male sporting one small claw and one large claw – the large claw is like a weapon which the male uses to defend itself and too attract the attention of the females. Females have two claws of equal size.
How Big of a Tank do Fiddler Crabs Need?
The ideal-sized tank for fiddler crabs depends on how many you intend to keep. If you have a small group of 4 crabs, then a 10-gallon aquarium should suffice. For each additional crab, ensure you add 3-5 gallons to help prevent overcrowding which can lead to aggression and illness.
Overcrowding can be highly problematic for a tank with fiddler crabs. Though typically peaceful in captivity, this species can become aggressive if their territory is encroached upon or there isn’t enough food to go around.
As well, overcrowding often leads to increased ammonia levels and an unclean environment which can promote both stress and illness. For this reason, a 5-gallon tank isn’t recommended for fiddler crabs, unless you keep just 1 or 2.
What is the Best Habitat for Fiddler Crabs?
Fiddler crabs are found naturally along soft sand near the edges of shallow salt marshes in the Gulf of Mexico. Mimicking this type of brackish environment as closely as possible will help keep fiddler crabs healthy and hardy in captivity.
A warm tank with half-salt, half-fresh water and a pH level of 8–8.5 is recommended. A water hardness of 12-30 KH with a specific gravity of 1.005-1.08 is most like the natural conditions this species thrives in. By maintaining these parameters, you’re helping to ensure the health and longevity of your fiddler crabs.
What Temperature do Fiddler Crabs Like?
Fiddler crabs prefer warmer water, somewhere between 75- and 85-degrees Fahrenheit. Therefore, a heater is required for their aquarium. Keeping them out of direct sunlight is also a good idea since this species is reclusive and prefers areas of coverage. Sunlight can also negatively alter the tank parameters.
The hardiness of this species is linked directly to their aquatic environment. If the water is too cold, then fiddler crabs will be become sluggish and may not live long. If the water is too warm, then you risk the increase in toxins which can alter the parameters and lead to disease or premature death.
Do Fiddler Crabs Need to be Fed?
Though fiddler crabs are scavengers and will feast upon algae, detritus, and other waste material in an aquarium, they still need to have fed them daily with some hermit crab food. Occasionally, you can offer them a few shrimp pellets. Keeping them well sustained will promote health while reducing aggression.
To keep your fiddler crab pets hardy and healthy in captivity, you must ensure they have enough food. If food is scarce, this species will become aggressive and fight for whatever edibles they can find. Just be sure to remove any uneaten food as soon as possible to prevent the water from becoming contaminated.
Are Fiddler Crabs Prone to Disease?
Fiddler crabs are quite resilient and don’t tend to suffer from any specific diseases in captivity. That said, they still need care by way of tank maintenance otherwise, they can become sluggish and sick if kept in a ‘dirty’ tank.
Bi-weekly partial water changes of 25-50% are recommended for a fiddler crab tank, provided you have a filtration system installed. If not, then you’ll need to perform 100% water changes at least 2 a month as this species won’t survive for long in a tank overloaded with ammonia.
What Factors Affect How Long Fiddler Crabs Survive in Captivity?
In terms of longevity and survival in captivity, fiddler crabs kept in a clean tank with plenty of room to forage will live longer than those that are overcrowded. Therefore, I recommend nothing less than a 10-gallon aquarium.
Regular tank maintenance is a must for this species. Like other aquatic creatures, exposure to toxins and high levels of ammonia will increase stress and ultimately result in illness or premature death. Routine water changes and a good filtration system are necessary.
Ensuring the water parameters are conducive to this species – one that mimics their natural habitat – is of vital importance. A warm, brackish environment with the proper pH and salinity (as well as soft, sandy substrate to burrow in) will help keep fiddler crabs safe and healthy.
Keeping fiddler crabs in an aquarium with suitable tankmates is a must. These invertebrates are small and calm which makes them easy targets for carnivorous, predatory fish. Housing them with peaceful, herbivorous fish (avoid bottom dwellers) is recommended.
Final Thoughts
To sum up, fiddler crabs are generally hardy and easy-to-maintain in captivity. All they need is the right aquatic conditions and a little care by way of feeding and tank maintenance. To enhance their longevity, mimicking their natural habitat as closely as possible is required.
I trust this article has provided all the information you need regarding the care and sustenance of fiddler crabs in captivity. Thanks for reading and good luck with your aquarist hobby.
