Starfish Deteriorating - Need Advise

[mb2007]

I have two blue starfish. A couple of days ago, one of them started to show some white pus at the end of one leg. I don't know if something bit him, he moved across a sharp rock and cut himself or he is just sick.
He has been getting worse since then. His leg seems to be deteriorating with small stringy pieces falling off. I have cornered off a section of my tank with plexiglass to separate him from everyone else.
Any advise on how to save him. All my water levels are normal with salt at 1.023.

 

[ophiura]

How long have you had these stars?
WHat are your SPECIFIC water parameters?
IMO, your specific gravity is far too low for stars. Ideally it would be 1.026
These animals need very large, very mature reef tanks with 125+lbs of LR per animal. For 2, I would suggest a 200+g with 250lbs of LR for long term success. They can not in general be spot fed, and will starve without this.
Most die within a month of acclimation shock. Many many more die within 18 months of starvation.
They start to disintegrate, at the arm tips. Yours is showing characteristic signs of either osmotic shock or starvation depending on how long you've had it.
Unless you are keeping it with triggers, large wrasses, and puffers, in which case it may be predation.
But this is unlikely I think.
These are some of the single most difficult animals to keep in smaller, younger tanks. Most will die shortly after being imported.
The primary hope is that this is a large mature reef tank, and that water parameters are pristine. I would start by slowly raising your specific gravity by topping off with saltwater.

 

[mb2007]

Here are my water parameters:
Ammonia 0
PH 8.2
Nitrite 0
Nitrate 10
I have increased my specific gravity over the past two days to 1.026.
I bought these two starfish from my local pet store about a week ago. The "professionals" there never gave me the good info you did. Otherwise I would have only bought one.
My tank is 75 gallons and it has been running about two years. I would guess that I have about 100 pounds of live rock. I only have small non-aggressive fish.
This morning I noticed some of this white material on two other legs. I though that some of it he was losing was just stuck to the outside. I took a toothpick and rubbed it against him to remove the material. I was shocked to find out that it not stuck on him but his others legs are also starting to deteriorate.
Since it probably is too late to save him, what is the most human way to put him out of his misery? Should I just remove him from the tank?
By the way, the other starfish is crawling in and out of the rocks and is healthy.

 

[ophiura]

This is acclimation shock and takes up to a month to start. Don't be too certain about the other star yet.
There are a couple of things you can try with the other one, depending on how much you care to experiment. It the deterioration is at the arm tips, you can try taking a razor blade and cutting above this to see if it stops. Stars can regenerate from this and now and then people report it helps.
If you wish to destroy it, the easiest is to take the star and put in a shallow container with seawater...just enough to cover it. In a corner of the container, add a tablespoon or two of epsom salt. Every so often, tip the container to dissolve and mix in some of this salt. This is an anesthetic, and will eventually kill the star. Similarly, freshwater can be used in a slow reverse acclimation.