Red Claw Crab: Molting or dying?

[PikminWorld]

Hello, I've had a female red claw crab for about 1.5-2 months now. She seemed to be pretty healthy and active up until this morning when I found her upside down and barely moving.

I freaked out a little and tried to help her thinking maybe she fell which in retrospect was foolish since crabs are pretty good at up-righting themselves. I consulted the Internet and most signs pointed to molting, which I had not seen her do before, so she must have been long overdue.

The issue, however, is that molting seems to be a process that should only last a few minutes, at most 15 according to some sites I read. She has been acting like this for hours now and I don't notice any cracks in her shell.

A few things about my aquarium:
It's 20G long, with a lot of rocks and plants providing hiding spots for the crab which I know they need for molting and feeling comfortable. The substrate is sand and I tested the water. No nitrites, no ammonia, and the nitrates were at most 5.0 ppm, which I read should be safe for crabs and other fish. The specific gravity of the water is around 1.004, slightly under the recommended 1.005, but hasn't seemed to bother her before. The pH is around 7.8 and the water temperature is in the optimal range, 77 degrees Fahrenheit. There is also a land platform on top of the rocks with some driftwood that provides her land to settle on, as I know they need more of a paludarium due to their semi-terrestrial nature.

Her diet consists of Hikari crab cuisine and occasionally frozen peas, which I admit should be a little more diversified, but there is also java ferns, java moss, and an anubias plant that she has been picking from before.

Her tank mates are all passive and were what I saw as recommended tank mates (at least in terms of fish):
1 Dalmatian molly
1 American flagfish
4 Nerite snails and A LOT of Malaysian trumpet snails for cleaning up the algae.
None of them try to attack her and have not been a source of stress for her in the past.

I am out of ideas and trying to research potential bacterial, fungal, or parasitic diseases for my crab (or any crab really) has proven fruitless. I have some medicine, but none that are designed for crabs specifically (I haven't been able to find any): ParaCleanse, Maracyn, and Ich-X. I believe ParaCleanse should not harm invertebrates and was thinking of using this if her condition does not improve by the morning.

Does anyone have any ideas what may be causing this? I apologize for how long this post is, but I didn't want to leave out any details that may help. Thank you so much for your time and any advice you can offer.

 

[Autumnsky]

Sometimes there is a failed molt and a crab will die. Has she been moving around the tank, and when you found her was she on the sand or the water?

Does she look bigger, brighter and shinier, maybe she was just finished molting. Have you seen a molt in the tank?

Are you using marine salt for SW fish/and or reefs?

 

[PikminWorld]

Sometimes there is a failed molt and a crab will die. Has she been moving around the tank, and when you found her was she on the sand or the water?

Does she look bigger, brighter and shinier, maybe she was just finished molting. Have you seen a molt in the tank?

Are you using marine salt for SW fish/and or reefs?

Thank you for the reply. Unfortunately, there is no molt yet. She has been moving her limbs/claw periodically throughout the day, but she definitely has not shed her exoskeleton yet. She was in the sand, but in the water when I found her.

I use Instant Ocean sea salt for maintaining my brackish water. Most of my aquarium creatures are "freshwater" but can adapt to brackish water conditions as long as the salinity isn't too high from what I've read.

 

[Autumnsky]

Good for the SW salt. I would do a partial water change just to make sure the salt, and sea minerals are available if she might need something more of. Keeping the water parameters very similar. As in more frequent smaller-ish water changes rather than one very large one.

Have you seen her molt often. They molt less when they are adult size since they don't need do the fast growing.

Was she an adult when you got her? If so, you can't be sure how old she is.

Hoping she perks up or gets the molting done and over with.

 

[PikminWorld]

Good for the SW salt. I would do a partial water change just to make sure the salt, and sea minerals are available if she might need something more of. Keeping the water parameters very similar. As in more frequent smaller-ish water changes rather than one very large one.

Have you seen her molt often. They molt less when they are adult size since they don't need do the fast growing.

Was she an adult when you got her? If so, you can't be sure how old she is.

Hoping she perks up or gets the molting done and over with.

Followed your advice to do a water change and unfortunately no change yet in her behavior. I have never seen her molt before in my 1.5-2 months that I've had her which seems strange.

I am unsure of her age when I purchased her, but she seems mid-sized, but not fully adult-sized yet. I can attach a photo later so you can see.

 

[Autumnsky]

Okay. Try another water change maybe. I just am not sure what it could be other than mentioned before. Age or diet maybe possibilities.