ruby green skinny

[gtownith]

my ruby green doesnt seem to be eating ive had him for two weeks and i havent seen him eat. he looks good no signs of stress all fins in tact and beautiful he just looks a little skinny, but he swims around opening and closing his mouth like he has something in his throat, but i dont see anything in his mouth. like i said he swims around just fine gets along with everyone.
i have 4dolphins one front and one lelupi.

[RustyNut]

Not eating and heavy breathing are possible signs of disease....