Nice jag ...i wish i could confidently say what sex your is but i still have doubts on mine ...yours has that strong lateral spotting that females retain while the rest of the pattern is faded..mine has a pointy reproductive organ but sometimes i wonder if i am judging it right...as far as the biggest in a group being male...i read someone else here say that the biggest they had twice turned out female the biggest a friend of mine ended up female and the other jag i have that was the biggest at the lfs looks now to be female... definitly keep the others you have and push their growth ...you might get supprised..usually the way i found out the fish i thought was male was not was to come to the tank and see it alone with its eggs...i hope we both get the fish we are looking to get..Adult male jags are very impressive...and yeah its hard to not feed mine two times a day...he begs like no tommorrw..i tred to go a few no feeding days and still ended up feeding it once...and then i feel compelled to get up nout of a dead sleep at 1am and do a water change...