a dragon goby sifts sand all over your corals a orange spot goby sifts sand over sand. i have one around 6" very big he can do my whole tank by the time out of bed he keeps my sand shiny. is a pain to sandbed corals though mine digs my elegance out and my clam out all the time.
they also build burrows under rocks so make sure your rockwork is stable.
i hated my dragon goby and gave it away for free.... ive come to love my orange
