Stella,
Who is the little yella feller there in front? Is that a watchman? If so, do you have a DSB? And lastly if it is a goby, and you do have a DSB do you have any problems with him destoying the sand bed and eating the fauna? They are one of my favorite fish but I had read not to have on in a DSB or all your DSB would do is feed the fish not perform the normal DSB functions.