Whats up with my star fish

So my starfish in my tank hasnt moved in a day or so and has some white stuff maybe sand around him and he doesnt look to good. idk if hes dying or not. i always get confused on how to tell if any inverts are dying. so is he dead or just not moving. Thanks brian

Sorry about the picture quality i took it from my camera phone cause i dont know where my sisters camera is at.

 

how long have you had him? Do you have reverse osmosis? and is it for a linkia genus?

 

Ive had him for just about 2 weeks. i dont have a reverse osmosis, do i need one? and its an orange linkia

 

if it hasnt moved at all in a day , id be worried. looks like the type that normally grazes on your glass and live rock? how longs your tank been up and running? most starts need an established tank to even have a chance of survival. also water params have to be kept very stable , they dont handle swings that well. is there any decay or flesh missing on its arms? also you ,ay have to pick it up and see if theres any movement in its sensors underneath its arms. i hope for the best here

guy

 

my tank has been set up for about 2 months. i made sure all the water conditions were stable and pristine before i put him in and nothing has changed with those. theres nothing missing from his skin except for the waterever thats been there for a couple days.

 

linkias are a tough star to keep. their mortality rate is quite low. but they can be kept. im thinking that your tank isnt old enough. not enough food basically for it. but for it to go in 2 weeks is kinda quick in that sense. could also be that it wasnt 100% healthy when you bought it. is there any movement whatsoever?

 

when i picked him up just now to see if i guess tenticles were moving i couldnt tell but he started to move his legs so i put him back down and he switched up position a little bit

 

do you have any wafers? if so , place one underneath him so he hopefully eats. did you place him on the rocks? thats probably the best place for him.

 

i dont have any wafers, and i placed him by the glass that i had some decent amount of algea

 

excellent idea . lets hope for the best. theyre an awesome star , and hope it comes around for you.