Watermelon fiddler crab

Care at a glance

Overview

The watermelon fiddler crab is a mostly peaceful crab for the beach of a brackish paludarium. It is best kept by someone with a little experience.

Caring for the watermelon fiddler crab

The watermelon fiddler crab spends most of its time out of the water, like every fiddler. Give it a paludarium with a deep sand beach, a shallow pool and a tight lid. A small group needs a footprint of at least 11 gal (40 L). The crabs dig, wave and sort sand all day at ground level.

It is sold as a freshwater crab and lasts a while in fresh water, but it is a brackish animal. Mix marine salt to a specific gravity of 1.005 to 1.015. Keep it warm, at 75 to 84°F (24 to 29°C), with a pH of 7.8 to 8.4.

It picks algae and detritus out of the sand. Feed sinking pellets, algae wafers, blanched vegetables and a little frozen food on the beach or at the water's edge. Add cuttlebone for calcium.

Keep a group with more females than males. Males spar but rarely hurt each other, and they ignore anything they cannot catch, which is nearly everything. Brackish snails are safe company, while fish are a poor match for a setup that is mostly sand.

Males carry a pink red claw. The larvae develop in the sea, which makes breeding it in captivity hard.

Good to know

The watermelon fiddler crab is Paraleptuca crassipes, in the family Ocypodidae, described by White in 1847 as Gelasimus crassipes. The trade knew it as Uca crassipes until the 2016 revision. Its carapace is usually about 2.5 cm across, crimson red with black patches. Sky blue patches mark the face and the area around the leg bases. Those colors are where the trade name comes from. It changes shade with the tide, darker by day and paler at night.

In the wild

The watermelon fiddler crab lives on the muddy sand of mangrove edges, lagoons and river mouths across the western Pacific. Its range runs from Taiwan and the southern islands of Japan through the Philippines and Indonesia to eastern Australia and the Pacific islands.

Common questions

Related species

• 

  Atlantic sand fiddler crab

  Leptuca pugilator

  1 in (2.5 cm) · 11 gal (40 L)

  1 in (2.5 cm)11 gal (40 L)68–82°F (20–28°C)

• 

  Fiddler crab

  Minuca minax

  1.6 in (4 cm) · 10 gal (38 L)

  1.6 in (4 cm)10 gal (38 L)75–82°F (24–28°C)
• Batik crab

  Metasesarma obesum

  1 in (2.5 cm) · 11 gal (40 L)

  1 in (2.5 cm)11 gal (40 L)72–82°F (22–28°C)

• 

  Brackish hermit crab

  Clibanarius longitarsus

  2 in (5 cm) · 16 gal (60 L)

  2 in (5 cm)16 gal (60 L)75–84°F (24–29°C)

• 

  Red claw crab

  Parasesarma bidens

  2 in (5 cm) · 10 gal (38 L)

  2 in (5 cm)10 gal (38 L)72–82°F (22–28°C)

• 

  African mangrove crab

  Goniopsis pelii

  2.4 in (6 cm) · 24 gal (90 L)

  2.4 in (6 cm)24 gal (90 L)75–86°F (24–30°C)