Fiddler Crabs

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General Information

The scientific name for the fiddler crab is Uca (species). Fiddler crabs make great additions to almost any aquarium. The fiddler crab family includes over 90 species and subspecies of the genus Uca. The gold fiddler crab is the most common fiddler crab found in pet stores. Gold fiddler crabs are attractive, fun to watch, and very entertaining. Male fiddler crabs have one large claw and the female has two equally sized smaller claws. The male fiddler crab will wave his large claw back and forth, making him look robotic. If people were told they are battery powered, many would believe this.

Housing your Fiddler Crab

Many people think that you can place fiddler crabs into full aquariums, but fiddler crabs need dry land to survive. Some people believe the land just helps the crabs be content, but it is a necessity for the fiddler crab to breathe air and dry out. Most people don’t want to have their aquarium half full of water, with wood or rocks sticking out above the surface. This creates problems such as hard water lines, filtration problems, water evaporation and is not very attractive or entertaining. Atlantis Under Water Islands are a perfect solution to the dry land problems aquarium owners encounter when it comes to owning semi-aquatic critters such as fiddler crabs, red claw crabs, newts and turtles. vCompatibility with other Fish Fiddler crabs are known to be more of a scavenger than a predator. You shouldn’t have to worry about losing fish when owning fiddler crabs. The gold fiddler crab is much less aggressive than other species of crabs. Under Water Islands allow you to feed your crabs in their natural environment with the feeder tube. This is amazing to watch. The crickets are trapped inside the Under Water Island at the bottom of the aquarium. This allows the crabs to hunt the crickets. This is great stimulation and a good source of food for the fiddler crabs.

Size and Life Span

An adult fiddler crab will grow to about 5 or 6 cm. (2 to 2.5 inches). The life span of fiddler crabs that are well cared for will be 2 to 3 years. A healthy crab will have some sea salt added to their water and dry land to dry out and breathe air.

Ideal Environment

To provide an ideal environment for fiddler crabs, you should have some marine or sea salt (never use table salt) to your aquarium. For true brackish water you need to have 2 tablespoons per gallon of water. If you don’t want to worry about having true brackish water, you can add half this amount of salt and the fiddler crab would still be fine. For fresh water aquariums it is good for the fish to have some salt added to the water. It helps the fish to have a protective layer over them, thus preventing diseases. Another very important part of an ideal environment is to have dry land for the fiddler crabs to dry out and breathe air. Fiddler crabs also need places to hide. The Under Water Islands provide dry land, fresh air and great protection. You can use the Feeder Tube to place food such as shrimp pellets or live crickets into the Under Water Island. This allows the fiddler crabs to eat at their own leisure and not worry about other fish trying to eat their food before they do. It is important to ensure that there are no holes of any kind at the top of your aquarium. Fiddler crabs may crawl out. Atlantis Under Water Islands have a product that seals up these holes. It is putty that is non-hazardous, waterproof and won’t ever shrink, crack or dry out.


Fiddler crabs aren’t as sensitive to water temperature as a lot of tropical fish are. Fiddler crabs will do fine in 65 – 85 degrees Fahrenheit. However, the fiddler crabs seem to prefer the water on the warmer side, around 80 degrees Fahrenheit.

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