there is no doubt some fish are super shy.....so I would just let him/her do what they are going to do. Either it will perk up some as it gets used to it's environment, or if it truely is stressed out, it will go downhill.
But if the fish is stressed, you messing with it, and forcing it out of the cave...will not "remove" any stress....and probably will actually add more stress.
My suggestion is just let it be. Instinct is too strong for a fish to give up eating when it has the chance...most will over eat when allowed. So a sure sign of an unhappy (possible sick) fish is not eating.
But if the fish is stressed, you messing with it, and forcing it out of the cave...will not "remove" any stress....and probably will actually add more stress.
My suggestion is just let it be. Instinct is too strong for a fish to give up eating when it has the chance...most will over eat when allowed. So a sure sign of an unhappy (possible sick) fish is not eating.