These do not Cap at 40 fishing im lvl 42 and skilling off these. from other fishing sites i have found they cap at over 50. you can sell them at about 300-400ish gil a pop depending on the NPC it seems. the guild pays the most for them if they are not full on there stock of Sazanbaligi. i was selling them to the guild in AU for over 400 then the closer they where to full the lower the price was.