1 kinds · tap one for a closer look
Semi-aggressive toward each other; do not keep in freshwater.
This one is best kept on its own, or with its own kind.
Semi-aggressive toward each other; do not keep in freshwater.
Not a freshwater tank animal. It needs brackish water or a setup that is mostly land. Read the care notes before you buy.
Good to know: Needs a beach area and brackish water.
Algae, flake and small meaty foods.
Tap a food to see what it is.
Males have one greatly enlarged claw (on either side) that they wave; females have two small claws of equal size.
Common problems. Tap one to see the signs. This is a guide, not a diagnosis.
Egg-bearing with marine larval phase ·
Females carry the eggs under the abdomen and release free-swimming zoea larvae into the water; the larvae pass several stages and can only be reared in marine water. Captive breeding is possible but rarely done.
Not practical.
Brackish paludarium with a sand beach.
Gravid female to seawater.
Thousands of eggs.
Planktonic larvae.
Small semi-terrestrial crabs whose males wave one giant claw. They come from brackish lagoons and shores; shops may sell them as freshwater crabs, but they cannot live indefinitely in fresh water and need a sand beach with brackish or marine water.
Fiddler crabs sold in the hobby come from several species and are usually not identified exactly. They have been popular as brackish-water pets because of the male's single oversized claw.
12 facts checked with sources
No valid species name: fiddler crabs in the trade are usually unidentified and come from several genera. The old genus Uca was split into 11 genera in 2016 (Afruca, Austruca, Gelasimus, Leptuca, Minuca, Tubuca, Uca, etc.). "Leptuca sp." is only right for American animals; Leptuca does not occur in Asia, so Indonesian imports (e.g. "Uca sp. Haribo") cannot be Leptuca. Suggest "fiddler crabs (Ocypodidae; former Uca), species varies". Invertebrate: semi-terrestrial brackish/marine crab.
Wikipedia: Fiddler crab · Wikipedia: Leptuca · Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabsNew value.
WoRMS / DecaNet record: Leptuca (accessed 2026-10-16) · Wikipedia: Fiddler crabCarapace width; varies by species (0.5-2.5 cm in Leptuca, 3-4 cm in the Indonesian "Haribo", up to ~5 cm in Afruca tangeri). Legacy 3 cm is a fair typical figure.
Wikipedia: Leptuca · Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabs · Wikipedia: Fiddler crab60 x 30 x 30 cm = 54 L for 6-8 crabs, mostly sand beach with water no deeper than 5 cm. Legacy 40 L.
Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabsNo minimum stated; source describes a group of 3-4 males and as many females.
Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabsMatches legacy "s".
Wikipedia: Fiddler crabSemi-terrestrial beach/mudflat crab; an aquarium zone does not apply. It needs a large sand beach (about 2:1 land to water).
Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabsNew value.
Wikipedia: Fiddler crab · Wikipedia: LeptucaMarine larval phase confirmed; legacy "not bred at home" is too strong, PFK says breeding in captivity is possible.
Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabs · Wikipedia: Fiddler crabSupports legacy text.
Wikipedia: Fiddler crab · Practical Fishkeeping (Frank Schaefer, June 2009): Fiddler crabs