Species description

Care, breeding and tankmates

Invertebrate profile

Diet

Detritivore

As a robust omnivore, Gelasimus vocans actively searches for both plant matter and meaty food items. They consume detritus, algae, and any small leftover scraps of food provided to the tank. Sinking wafers and chopped seafood can supplement their daily scavenging.

Ecological role

Scavenger

Gelasimus vocans serves as a highly effective scavenger, breaking down larger pieces of organic waste. They aerate the substrate with their movement and control nuisance algae growth. Their constant activity maintains the health and cleanliness of the benthic zone.

Shock sensitivity

Medium

Gelasimus vocans should be acclimated carefully to avoid the shock of rapidly changing water parameters. Wide fluctuations in salinity or temperature can compromise their immune systems or trigger premature molting. Consistency in water quality is paramount for their long-term health.

Calcium and minerals

Medium

Sufficient calcium availability is an absolute requirement for Gelasimus vocans to maintain its hard carapace. Poor calcium levels can cause incomplete molting and eventual death. Feeding calcium-enriched diets and keeping minerals in balance is vital for their exoskeleton strength.

Molting

Yes

During molting, Gelasimus vocans sheds its old shell to allow for growth and regeneration of lost limbs. It is entirely soft and defenseless during this process, requiring secure caves or crevices for hiding. The old molt should remain in the tank so the crab can recycle the calcium.

Reproduction

Oviparous

Rearing Gelasimus vocans in an aquarium is generally quite difficult due to their complicated larval phases. Females carry dense clusters of eggs on their abdomen before releasing them as planktonic zoea. These microscopic larvae usually require separate rearing vessels and very specific live foods.

Compatibility & tankmates

Community

Gelasimus vocans is generally safe with fish that are too large to be eaten but too small to view the crab as prey. Certain predatory species of fish should be entirely avoided. Be cautious when keeping them with slower bottom-dwelling species which might be pinched.