Mmmk, well first, what do you mean "Free him from captivity"?? Please explain. Secondly, it's natural for fish to flee to the nearest hiding spot available when first introduced. It's like that "new kid in school" thing, where you just want to blend in with the wall that first day. It's a stressful situation and one that can only be amplified if the fish were not acclimated properly. Were they?
Additionally, you say that you believe the other clown is in your larger set-up, so if I assume correctly, these fish were added to different tanks?
One good way to help ease the stress on these guys is to turn off the lights for a few hours (or simply leave the actinics on so it's not as harsh), and you can also try feeding them. Garlic guard is a great response inducer, so if you first want to see if they'd be receptive to food (as to avoid fouling your waters with uneaten bits), then you can add some of this to the water and they may respond and quickly come out of hiding.
Keep a lookout, but allow them some time to settle and regain their composure. Moving rock and digging around trying to find them might only stress them out more.