Fishes in the Sea

My office has a water feature with a few fishes living in it. Those fishes are the most timid fishes I have ever seen. They "fee-eew" off to hide when they see somebody looking at them. Once I decided to feed them. I purposely waited silently after pouring the food in to see if they will come out for the food. So after a while, I saw them shooting out of their hiding place one by one to grab the food, then shooting back to the hiding place immediately like some kind of covert op.