Burrito, are you deaf? I'm not being mean to ask. I had a fellow visit once, he was deaf and I couldn't make out his words, so I asked him to write it out and even then I couldn't make sense of it.
If I can at all translate what you are asking, a fjgi rock is the right type of rock. It is not however enough to keep the mandarin happy. The rock makes the fish feel more at home, that's why he seems to like it and is staying close to it. There is not enough copepods on the rock to keep a mandarin alive. They eat thousands of copepods everyday.
If you buy a bottle of copepods the are maybe 200 in it. Those bottles are just starter kits, it is not enough for the mandarin to live on. A refugium takes months to let the little copepods grow in enough numbers to keep a mandarin alive. You would have to have the refugium up and running or a long time before you put a mandarin in your tank.
Once these fish begin to starve they get to where they can't eat, even if you put him in a tank loaded with copepods his tummy is too shrunk to eat.