Mine can be that way too. Out in the open for days and then gone. They can survive quite well with the littlest pieces of food. Mine will wait for fragments to float into its hiding place or dart out and get them and then right back into the cave. My Pygmy wrasse is about 3 months in the tank and it never comes out. I see it up in the caves but it’s surviving just fine. I feed foods that go from chunks for the bigger fish to very tiny for the anthias so lots float under the rock work. Home delivery!