Starfish Arm decay?

On Sunday before leaving for work, i noticed my choc. chip star was in the same place as he had been for a few days; which is odd as he is usually quite mobile.
He had somehow got wedged under one of my rocks, and was trapped. As i freed his arm i noticed he had some scratches where color had been stripped off, leaving white spots.

Today i woke up to find him like the pictures below, much more of his arm is white and it looks like the flesh is falling out. Anyone got a clue as to what's happening? He ate well yesterday, having his usual mussel and clam strip.
My params are Amm. 0
Ph 8.4
NiT 0
NiA 20
Just added a skimmer which is just breaking in, wondering if that could have anything to do with it?

 

Not sure what NIA is ? and have you had it long ? and what type is it and have you ever tested for voltage in the system ? some tanks just produce far to much voltage naturally from reactions of rock minerals and salt like little batteries

 

AHHH the Bagdahd Battery

 

NiA= nitrates, and it's a chocolate chip starfish. Never tested for voltage. If that was the case wouldn't i have other dead or dying animals?
I've had him in my 4 month old tank for about 3 months, no problems, ever. eats well and is constantly on the move. Well before the arm thing.

 

anyone? please?

 

Sounds like it got an infection from the injuries from the rock. Not sure how to treat a star fish. Also a 4 month old tank might be to young for a star. They like really stable and pristine water parameters.

 

My blue linkia did the exact same thing, it looked like he was trapped under a rock and the next day his leg fell off. I was told that they prefer a more established tank, my tank was only 3 months old when I introduced him. He died within a couple weeks after losing his leg. Sorry, and I am not sure if all starfish act the same.

 

I'm certainly no authority, but it might be something to consider cutting the dead/dying arm off rather than have that problem spread to the center and kill it outright?

I know it would be hard for me to cut an arm off a living starfish... but who knows, if it saves the life, might consider it?

Don't do it unless someone with more knowledge chimes in... but I know some stars shed arms, and I have seen biologists propagate them by cutting an arm off and chopping that arm up into 20-30 chunks and each chunk becomes a new (if sort of silly looking) starfish.

 

Went to work and now at 11pm the whiteness is spreading to his other arms. I'm way too sad!

 

dont starfish grow a new arm when one gets cut off by a predator or other natural ways??? got a scalpel? i dunno just a thought...