I believe I have a solution to this...I hope
My baby beardie chomper, used to swim in the sink fine, and then all of a sudden he changed his mind and would freak out if I take him any where near the sink.... I thought oh no...this is it, he's guna hate swimming/
bathing for ever now :/
HOWEVER... I brought a large exoterra water bowel (which is cool cause as he's a baby he can still swish around) and his attitude COMPLETLEY changed to the point that he kept taking himself in there & swimming and splashing, little to say he loved it !!
Bottom line is, I think perhaps what he is currently being bathed in is too big and its freaking him out.. Are the temps ok-not too hot/cold? You could you try a baby
bath(if hes an adult) or dish if baby...? because then he can get out on his own and because of that, will be more willing to stay in... but I really would suggest getting a baby's
bath instead and I really think he'll be ok with that! Keep me updated !

hope this helps...but don't worry you will find something he's comfortable in!