my fantail synodontis is shy as well, if you really want a shy fish to come out, without stressing it, just bump back your normal feeding time. I did this during the winter (gets dard earlier) and as spring came, it got lighter in the afternoon (when i feed them) yet all of the fish got ready to eat at the same time, and when daylight saveings came along, i ajusted my feeding time again to where i feed them at the same literal time. Now all of my fish, including the nocternal ones are ready to eat, even before its dark out.