Just an update
Morpheus is doing really well, the funny egg mound thingy it still there, and nothing I do will change that. Just noticed he had a bit of fungus almost suspended in his slime coat so he's getting salt baths again, but otherwise he's become nice and tubby, eats anything and everything and is doing great. I recently lost Pendragon, so once the tank is sterilized Morpheus will move out of his tub into the glass tank.
His gills are growing back in, with plenty of filaments and he looks kinda odd missing most of his dorsal fin and his weird eyes, but he's doing great.