My star fish is acting weird

Question
QUESTION: I am so scared right now for my starfish. A little over a week ago, he got a hold of a snail and ate it, i thought that was great because it was a big meal for him, but since then (two friday's ago) he has been acting different, He doesnt move often, if at all during the day, he is now staying on one spot in the tank, when before he would move around. he is in the tank at work (my bosses) and every day we came in, he was in a different spot. not anymore, not just that, but his legs are all curled up and he just stays like that, his suctions still come out, he isnt wasting away, but something isnt right, he isnt acting the same. I was told to tip him on his back and see if he tipped himself back over. he did, but it took a whole lot longer than when he falls off the side and tips back over. He isnt meliting or wasting away, he is more doormant, I am not an expert, so i cant tell you water stuff or ph balances or whatever, i just knwo he ha sbeen in there for a few months and i am sad cause i dont want to lose him. our serpant star comes out more than he does now and he is nocturnal, PLEASE HELP

ANSWER: Hello!

If you knew the parameters. or even the type of starfish I may be able to give a more accurate guess. But with the only info I have to work with is that he is a starfish, I can't really give any accurate advice.

-Nick

---------- FOLLOW-UP ----------

QUESTION: it is a red knob african starfish, the tank is 125 gallons, i came in today and he was all shriveled up (when office lights were off) I started crying, then an employee turned the lights on and he spread out a bit, is he acting normal, he doesnt seem to be

Answer
Ah, very nice starfish!

The red knobs are also very well known for being EXTREMELY sensitive to changes in water parameters. I am guessing that it was either a change in pH, salinity or temperature, or even possibly a feeding problem that is shocking him.

When performing water changes, do them very slowly.

Perform all salinity tests with a high quality refractometer (if you aren't already), and make sure the readings are exactly the same as the tank.

Frequently test the pH of the water to make sure it is staying the same.

-Nick