Pom Pom Crabs should be acclimated gradually because shipping water and aquarium water can differ in temperature, pH, hardness, TDS and possibly salinity. The goal is to reduce the size of that change without leaving the crab sitting for hours in deteriorating shipping water.
Prepare the destination tank before opening the bag. It should already be cycled, escape-resistant and within the water range you intend to maintain. Acclimation cannot rescue an animal placed into an immature aquarium.
Before Opening the Bag
Turn the aquarium lights down. Verify the filter is operating and test ammonia and nitrite if the tank is new or recently changed. Confirm that the lid, filter gaps and cords are secure because a newly introduced crab may explore intensely.
Have a clean container, airline tubing or a small cup, a thermometer and optionally a TDS meter ready. Avoid using containers that have ever held soap or household chemicals.
Step 1: Match Temperature
Float the sealed bag briefly or place the shipping container in a stable room while comparing temperatures. The goal is not to leave the animal sealed for a very long period; it is to remove a large temperature difference before chemistry acclimation begins.
If the bag is extremely cold or hot, correct temperature gradually rather than moving it instantly to the opposite extreme.
Step 2: Compare Water When Practical
Measure aquarium temperature and, if you have the tools, TDS and pH. Shipping water readings can be less stable after transit, but they still give useful context. A major difference suggests using a slower transition than when the two waters are already similar.
Because aquarium-trade Ptychognathus identification and natural salinity are not perfectly resolved, do not suddenly convert a freshwater-shipped crab to brackish water during arrival unless the supplier has specifically maintained the animal that way and you prepared a matching destination.
Step 3: Begin Gradual Water Mixing
Move the crab and shipping water to a clean acclimation container if needed. Add small portions of aquarium water over roughly 30–60 minutes, adjusting the pace to the size of the chemistry difference and the animal's condition. A slow drip can be used, but it is not necessary to turn every acclimation into a multi-hour process.
Keep the container covered enough to prevent escape while allowing air exchange. Pom Pom Crabs can climb smooth-looking surfaces more effectively than many keepers expect.
Why Extremely Long Acclimation Can Backfire
Shipping water contains waste, and once a bag is opened the chemistry can change. The goal is to reduce parameter shock, not to hold a stressed crab in stale water indefinitely. If the animal appears severely distressed, prioritize clean, appropriately matched water and oxygenation over an arbitrary acclimation timer.
Step 4: Transfer the Crab, Not the Shipping Water
Use a small cup or soft net to transfer the crab into the aquarium while leaving most shipping water behind. A cup keeps the animal submerged and reduces the chance of legs becoming caught in mesh.
Do not grab the crab by a leg or claw. Crustaceans can autotomize appendages under stress. If it is holding the container, let it release rather than pulling.
Step 5: Keep the Tank Quiet
Leave the lights low for the first several hours. Avoid rearranging hardscape, adding new fish or performing another large water change on the same day. The crab may disappear immediately into moss, wood or rockwork. That is normal.
Do not repeatedly search for it by lifting stones. Hiding reduces stress and is especially important if transport triggers a molt.
Should You Feed Immediately?
A small amount of food later the same day is reasonable if the crab is active, but a heavy feeding is unnecessary. New arrivals may not eat immediately. Remove uneaten concentrated food before it decomposes.
Once normal foraging resumes, follow a consistent varied diet rather than relying on leftover fish food.
What Normal First-Day Behavior Looks Like
Hiding, slow exploration and occasional climbing are common. A crab may remain out of sight until the room is dark. Color can look slightly different under new lighting or after shipping.
More concerning signs include loss of coordination, lying upside down without correcting itself, repeated group-wide attempts to leave the water, or persistent inactivity combined with poor water readings.
If Several Crabs Try to Escape
Test the destination aquarium immediately. Check ammonia, nitrite, temperature, pH and oxygenation. Confirm that dechlorinator was used correctly and no medication or cleaning chemical contaminated the tank.
One crab exploring the lid is not the same as an entire group acting distressed.
Do Not Medicate New Arrivals “Just in Case”
Preventive medication can expose an already stressed invertebrate to additional chemicals. Many fish treatments, especially copper-based medications, are inappropriate for crustaceans. Quarantine and observation are safer than indiscriminate treatment.
Acclimation Checklist
- Cycle and prepare the destination tank first.
- Secure the lid and equipment gaps.
- Dim the lights.
- Match temperature gradually.
- Compare TDS/pH when practical.
- Mix aquarium water into shipping water gradually.
- Keep the acclimation container escape-proof.
- Transfer the crab gently without dumping shipping water into the display.
- Keep the tank quiet for the remainder of the day.
- Observe behavior and water quality.
Related Pom Pom Crab Guides
Complete Care Guide • Water Parameters • Filter, Heater and Lid • Why Pom Pom Crabs Hide
Frequently Asked Questions
How long should I acclimate a Pom Pom Crab?
Often roughly 30–60 minutes is a practical starting window, adjusted for how different the waters are and how the crab is behaving. Avoid unnecessarily prolonged exposure to opened shipping water.
Should I drip acclimate?
A drip is useful when chemistry differs substantially, but controlled small additions of aquarium water can also work.
Can I add salt during acclimation?
Do not abruptly change salinity on arrival unless you know the supplier's water and have a specific matched plan.
Why did my crab hide immediately?
Hiding after transport is normal. Give it time and avoid tearing apart the aquascape.
Should I pour the shipping water into the tank?
It is better to transfer the animal and discard most of the shipping water.
Sources and Further Reading
- Aquatic Arts: Pom Pom Crab husbandry and salinity discussion
- ZooKeys 2025: Ptychognathus taxonomy and habitat context
Acclimation Is Only the First 60 Minutes
The hours after release matter just as much as the mixing process. Keep the lid secure, leave the aquarium lights low, and avoid adding other new livestock on the same day. A crab that has just been shipped needs time to explore the tank and find cover without being chased or repeatedly disturbed.
Check the aquarium again later that evening. Make sure the filter is running, temperature has not changed, and the crab is able to right itself and walk normally. If the animal is hidden, do not assume something is wrong; hiding is one of the most common post-shipping behaviors.
When a Slow Acclimation Is Especially Important
Take extra care when the crab came from water with a very different TDS, hardness or salinity, when the shipment was delayed, or when your destination water is made from RO plus remineralizer. These situations increase the chance that the source and destination water differ substantially. Measure what you can, change conditions gradually, and avoid turning acclimation into a chemistry experiment.