Should You Move Adult Vampire Crabs After the Babies Appear

Yes. If you want the babies to survive in any number, move every adult vampire crab into a second, fully set-up paludarium and leave the crablets where they hatched. Adult vampire crabs eat the crablets they catch, so splitting the two generations raises the most young. In a large, densely planted paludarium some crablets do grow up alongside the adults, but you should expect to raise fewer.

When can vampire crab babies stay with the adults?

Only in a big, densely planted paludarium, and only if you’re fine with raising fewer of them. Keepers who leave crablets with the adults in large planted tanks do see young grow up there, because the babies have room and cover to stay out of reach. In a small tank, or one with open ground and few hiding places, separate them. Don’t count on vampire crabs breeding more in a smaller tank, either.

The difference can be large. One keeper who raised broods both ways got two to five crabs to adult size when the young stayed with the adults, and around twenty when they were kept apart. Raising a brood apart can quickly mean too many vampire crab babies for one tank.

So it comes down to what you want from this brood. Want a tank of young crabs? Separate them. If you only want a few to grow on and you’ve got a large, heavily planted setup, leaving them can work. Thicken the cover first with extra moss, leaf litter and small hides near the water’s edge.

Is it easier to move the adult vampire crabs or the crablets?

Moving the adults is usually easier. You’re catching a handful of crabs you can actually see, instead of a clutch of up to about 40 crablets tucked into moss and substrate. It also leaves the babies in the tank they hatched in, with no handling at all.

Newly hatched crablets stay on or under their mother for a short time before they wander off, so look at her before she goes into the new tank. You don’t want to carry babies across with her.

Moving the crablets makes sense when there are only a few, or when you can’t give the adults a second tank of the right size. Keepers who do it lift the young into a separate grow-out tub. That tub needs everything a paludarium does in miniature: damp land, shallow water they can climb out of, cover and a lid with no gaps.

Set up the second vampire crab enclosure before you move anyone

Treat the “temporary” tank as a full paludarium, because the adults will live in it for months, not days. A plastic box with a water dish isn’t enough for that long.

An adult kept apart for weeks may well need to molt in the new tank, so build that water section in from the start.

• Land with damp substrate the crabs can dig into, and hides on land as well as near the water. Where a crab molts can differ between kinds of vampire crab, so give them both options.
• A water section a crab can fully enter and walk back out of.
• About 78°F (26°C), inside the 72-85°F (22-29°C) band the adults already live at.
• Humidity held up with a closed lid, moist substrate and moss, and misting about once a day.
• A lid that closes tight, with every cable and tube gap blocked.
• A hiding place for every crab.

Moving a few of the adults’ own hides and plants across helps, so they aren’t starting in a bare box. Check every piece for crablets before it goes over. Everything else in the new tank follows the same vampire crab care as the old one.

How to move adult vampire crabs without taking babies with them

1. Move them as soon as you spot the babies. Every night the adults stay in, they have another chance to catch one.
2. Look for the adults in the evening or early morning. Vampire crabs are mostly out then and hidden for much of the day.
3. Herd each crab into a cup or small container instead of grabbing it, then check the container for crablets before you tip the adult into the new tank.
4. Count as you go. You need to know how many adults you have, because a female carrying eggs often stays dug in and is rarely seen. If you do find one, you usually don’t need to separate that pregnant vampire crab from the others.
5. Keep looking over the next few nights until every adult is out. One missed adult can still thin out a brood.

How long should adult vampire crabs and crablets stay apart?

We’d keep them apart until the young are close to adult size. There’s no agreed size at which crablets become safe with adults, so waiting longer is the safer mistake. In practice that often means running both tanks for good.

Keep an eye on the adult tank as well. A female carries her eggs for about three to seven weeks and spends most of that time hidden, so one of the crabs you just moved may already be carrying the next brood. If babies turn up in the adult tank, you’re facing the same choice again. Next time, if you spot a female carrying eggs, you can move her on her own before her young appear. Planning for the next brood is part of ongoing vampire crab breeding.

The same rule holds when you add crabs later: new vampire crabs go in with the adults, never into the tank that’s raising crablets.