I have a JD that was in a tank with larger JDs when I bought him, he is 5 inches in length and is looking healthy. He goes after the sinking food I drop if he sees it falling, but he won't come up to the top for pellets and whenever I come near he goes back into one of his caves. I know some of this is just aclimating to the new tank, but how long does it ussually take and is there any way to encourage him to come to the top of the tank, thanks?