+1 to dip n feed regularly when they are in this state. I have rescued several plates and brought them back to full health by doing this. Feed them every 3 days then after they start looking better go to once a week. IME, some plates like sand, some dont, high light, low light, all mine prefered medium flow however. Hope you can pull it through. If however it doesn't make it, dont ditch skelly as they can grow babies from it once dead.