Looks like P. apogon is it. This specimen definitely needs fattening up. Should be a nice display cat when he gets near his 2ft+ adult size. Keep us posted on his growth.
Good eye I largely skipped Phalacronotus because of their very characteristic head and shoulder/back shape. A good side shot would have been helpful from the start - all we are getting so far are the pics from semi-above which don't show the characteristic rise from head to back. But yes, they lack a dorsal altogether.