Counterintuitive as this might seem at first blush, one of the things you absolutely must do to get better photographs of marine life (or anything in nature, actually), is to invest as much effort as possible into looking, as opposed to pressing the shutter.
The more time you spend watching a fish, crab or whatever, the more you insight you'll get into it habits, territorial preferences if any, and "personality" as such. As time passes (without your attempting to shove a lens in your subject's face or hammering it with a thousand strobe flashes), the subject of your attention may actually grow accustomed to your presence and demonstrate interesting, perhaps even unique, behaviour.
Recently at Loloata, I spent nearly an hour with a very small goby. It was most likely a Tomiyamichthys oni, though the photos I've seen of this fish in guidebooks and online don't show a blue spot together with the dark splotch on the dorsal fin, which the little fish I was watching did have.
In all other respects, it resembled at T. oni...tiny (about 2cm), shy, with a tendency to move rapidly in random directions. It's difficult to know for sure, as very little information in general is available about the Tomiyamichthys genus (as is unfortunately the case for many other marine animals).
What was truly special about this particular fish wasn't the unusual blue marking however. It was the unusual and entertaining behaviour it demonstrated.
Normally, when gobies like this feel threatened or annoyed, they disappear in a blink into their burrows, or they might swim away so quickly that you can't figure out where they went.
This one didn't seem terribly bothered with my presence, though it did disappear into its hole a couple times. I waited patiently, and it reappeared each time, satisfied that I wasn't a threat.
Once we established a certain level of trust, the fish ventured relatively far from its hole, perhaps two metres or so...a bit at a time, stopping along the way to grab a mouthful of dirt, or just to look around.
At one point, the goby seemed to realise that it was quite far from home. Stopping dead in its tracks, the fish stared straight at me, then amazingly, ducked down to lay flat on the sand, as if to hide. It worked.
Without the aid of artificial light, it was nearly impossible to discern the extremely well camouflaged goby against the sand when the fish was in this prostrated position.
With the help of a macro lens, I kept tabs on the goby as it alternated between lying flat on the sand and raising its head a bit to take a peek around. After five minutes or so, the fish finally tired of this game and bolted back to its burrow, leaving a puff of sand in its wake.
I've never noticed anything like this before, but I'll wager there's a decent possibility that this is a common strategy employed by gobies like this, given their mottled-sand colouration and pattern, which makes it easy for them to blend into the substrate.
Has anyone else witnessed similar behaviour before?