Salt water blue crab

I have a salt water blue crab that we got from the Chesapeake Bay. We've had him for 7 months and he's gone through two molts. He seems to be actiung funny now. He's lost both claws. When you go to touch him, he moves away. Anyone know if this is a molting phase?

 

What is the salinity of the tank?

 

The Salinity is 1.023. We have another Blue Crab and she is doing fine. As of today, it looks like our little Blue crab might have bit the dust. We'll see if it finishes molting, if that is truely what is happening. Trates=40, trites=0, pH=8.2 Amonia=.25

 

Sounds like you have some issue with your water there your ammonia should be 0. although I will admit if you are using an API git or something the 0 and .25 look very similar in SW so it could be a misreading. Nitrates a little high but nothing that would kill fish or crabs. you SG is a little low too is this a brackish crab? I would raise it to 1.025

 

Blue crabs do not do well in dirty water and since their feeding habits tend to make a mess of the aquarium.IMO they are not a good choice for captivity unless agressive maintenance of the tank is sustained.Your Nitrates are an issue.These crabs also do not like a low PH.Anything under 6 is lethal. Blue crabs are found from the mouth of the Chesapeake Bay to tidal fresh areas. There are distinct differences in the ranges of males and females. During the summer months, males are found from freshwater to the polyhaline zone (waters with salinities of 18-30 ppt), although they occur in the greatest numbers in salinities of 3-15 ppt. Maximum numbers of females occur down Bay at salinities of 10 ppt to ocean salinities.

 

Agreed with the above.

Another possibility is temp stress. What is your tank set at? The Chesapeake Bay and northern Atlantic don't get anywhere near tropical temps.

 

Water temperature requirements vary and are considered important, but no optimal range is reported.
When air temperatures drop below 50°F (10°C), adult crabs leave shallow, inshore waters and seek deeper areas where they bury themselves and remain in a state of torpor throughout the winter. Blue crab growth is regulated by water temperature. Growth occurs when water temperatures are above 59°F (15°C). Water temperature above 91°F (33°C) is lethal. Blue crabs are susceptible to sudden drops in temperature.
Salinity is important, but requirements vary by life stage. Generally optimum is 3-15 parts per thousand (ppt).
Heres a good link about Blue crabs.

http://www.bluecrab.info/lifecycle.html

 

Yup we read up on the same information. Our male Blue Crab has passed away. Amazingly, the female is doing very well. We do water changes twice a week. We're pretty aggressive with that. Also, we took a water sample from the Chesapeake bay and had our LFS test the water. Funny part was that the Amonia was much higher than what we had. The pH was lower than what we had, but the Trites and Trates were dead on. Our temp is 75 degrees. We're going to drop it a little bit more. Our female has molted twice and is now 3 times the size from when we got her. She was about an inch long. Now she's 3 1/4 inches. We'll see how the female does. Thanks for all the information