A crab sitting motionless in the water, or one that’s simply gone? Check for a molt first, because a vampire crab (Geosesarma) that sits still in the water or seems to vanish may only be molting. Newly bought crabs often die within about two weeks of arriving, and that loss is mostly put down to their condition after import, shipping and handling. In a tank that’s been running a while, look at moisture, fights, temperature and water access. Whatever you find, don’t lift a crab out until you’re sure it’s dead.

Is your vampire crab dying, or just molting?

Check for a molt first, because a vampire crab that sits still in the water or seems to vanish may be in the middle of one. In our paludariums, vampire crabs go into the water to molt and stay down there for a few hours. Is yours sitting quietly in the water? Then look from where you stand and don’t lift it out. If a crab has simply vanished, count your crabs again over the next day or two before you dig under the hides.

The shell a crab leaves behind can fool you too. A vampire crab’s shed looks like a whole crab, legs and all, but its eyes are empty, see-through shells, it’s hollow, and the back of the shell lifts open. That’s a normal part of vampire crab molting, so there’s nothing to treat and nothing to pull out yet.

What to do when a vampire crab stops moving or eating

Give it time and watch from outside the tank. A crab that sits still or skips a meal isn’t, on that alone, a dying crab. Leave a little food near where it spends its time, check later whether any has gone, and lift what’s left before it spoils. Keep your hands out of the water while a crab is sitting there. If food keeps going untouched, vampire crab not eating covers what’s normal for a new or molting crab.

Why do new vampire crabs die in the first weeks?

Newly bought vampire crabs often die between arrival and about two weeks later, even in a tank where other crabs are doing well. Some arrive dead or weak, and others die within days. You should still check the tank, but after these early losses it mostly turns out fine, and the cause is put down to the crab’s condition when it arrived, after import, shipping and handling. The other thing to check is plants: rinse anything new, and leave out plants that may have been treated or fertilized.

What can you actually control? The part that comes before the crabs do. Build the land and water and run them before you order, so new crabs go into a vampire crab tank setup that has already settled, with damp land and water they can climb in and out of. When they arrive, follow the instructions supplied with your order. One keeper reports a new crab that was slow after transport and moving normally again the same day, so give a slow newcomer a day before you decide anything.

Is your vampire crab blowing bubbles because the tank is drying out?

It may be, so check the moisture first when you see bubbles or foam at a vampire crab’s mouth. Press the moss and the substrate, and both should feel damp. The lid should be closed, and every crab should be able to reach the water. If any of those is off, fix it today.

In land crabs generally, the gill chambers hold water, most water is lost through the shell and the gills, and a crab that dries out takes in less oxygen because its gills collapse.¹ One field study of wild vampire crabs in Java reports that when a crab’s body starts to dry out, it releases fluid that shows as foam or bubbles, often at the mouth.² So foam doesn’t, on its own, tell you a crab is ill or dying. It tells you to check how damp the tank is.

Why is your vampire crab missing legs?

Vampire crabs in a group often lose legs and claws in fights with each other, most often when a dominant male chases or attacks the others. A crab can lose anything from one leg to both claws and several legs this way. Lost legs and claws grow back at a later molt, often smaller and paler at first. In our tanks, the sign that one is coming back at the next molt is a small bud of flesh at the spot where it was lost. One keeper moved two crabs that had lost both claws and a few legs into a separate tank, and after a molt one of them had both claws and a new leg again.

What helps is space. Give the crabs enough hides that every one of them can get out of sight at once, so a crab that’s being chased has somewhere to go. If one crab keeps getting pushed out of cover, your land may be holding more crabs than it can, and how many vampire crabs can live together comes down to exactly that.

Check the temperature and water access for the vampire crabs that are left

Put a thermometer at crab level and keep the vampire crab tank at about 78°F (26°C), inside 72-85°F (22-29°C), day and night. Then look at the water section. Can every crab climb in, get fully under and walk back out? Steep sides or a drop with no easy way up are worth fixing now, before the next crab goes down to molt.

If crabs keep dying one after another, go through the lid, humidity and crowding as well, the same checks that everyday vampire crab care asks of your tank.

When to remove a vampire crab you think is dead

Remove a vampire crab only once you’re sure it’s dead: its eyes are still in place, it’s full inside and it soon smells. A shed has none of those, and a crab that’s still in the water may be partway through a molt, so don’t lift one out of the water to check. Not sure yet? Give it a few hours and look again. A dead crab soon smells, and a shed smells of nothing.

Once it’s out, run through the checks above for the crabs that are left. If crabs keep dying and every check passes, ask an aquatic vet or an experienced local keeper to look at your setup. Even a single vampire crab that died suddenly is worth those checks.

Restocking with tank-bred vampire crabs

When you’re ready to restock, you choose Male or Female for each crab on the product page when you buy tank-bred vampire crabs. Everything in our catalog is bred or propagated in our own tanks rather than collected from the wild.

Film the unboxing in one take when the box arrives. Livestock that arrives dead is replaced free of charge, counted from the first animal, when you report it within 2 hours of the carrier’s delivery time with an uncut unboxing video. The full terms are set out under the live arrival guarantee in the warranty policy, and the instructions supplied with your order cover the first hours in the tank.