Anna and Ned DeLoach at blennywatcher.com never fail to astound us with their photos and videos on their tropical adventures. In this video Anna recounts their observation of an endearing pair of Signigobius biocellatus breeding in the silty muck of Papua New Guinea.
Not only fun to watch, this fish has some pretty inquisitive reproductive behavior. Signigobius biocellatus feeds by sand-sifting so we find them just off reefs or near shorelines in silty, nutrient-rich sand. We have seen them from Palau through Indonesia, so they aren’t really uncommon, but their populations are certainly not thick. Almost always found in pairs, they tend to be a bit suspicious, springing off speedily to their burrows if we advance too closely.
A few years ago, on a house reef dive at Tawali Resort in Papua New Guinea, they were pleased to find a busy pair that didn’t seem to be bothered by their presence. Their friend Claire Davies, Ned and Anna watched for over 90 minutes as the little gobies worked as a tag team, excavating several different burrows with their mouths and rapidly fanning with their tails, pausing intermittently to scoop up a mouthful of sand to feed.
The next day, they led a few friends to the site where they had watched the little gobies the day before but now there was only one! They looked everywhere, but no mate – just a single Signal Goby, bouncing around feeding, as if nothing were amiss. They wondered about the vanishing of the fish. Ned said a snapper probably ate it. Yeah, well that could have happened but this was a fully grown fish that had survived out on the sand long enough to find a mate and dig all those burrows. They imagined a family spat or maybe a home wrecking third party (In the Caribbean, they had once observed a mated pair of Hamlets break up over a third hamlet and reunite a few days later – there are all kinds of thrills down on the reef).
Always the optimist, Anna went back out the next morning to look for it again, but still found just the one. Then at lunch, Claire reported that the missing Signal Goby was back! After interrogating her carefully to make sure she had been in the same spot, Anna went back to see and sure enough the reunited pair was bouncing around, digging and pecking at each other. An online search turned up a paper from a 1977 study that explained the disappearance: after the female lays eggs in a burrow, she seals the male in, releasing him periodically over the next few days to assist with burrow maintenance. Now wouldn’t it be fun to have a “burrow cam” to watch all that! They wrote about their experience in the Winter 2010 issue of Alert Diver: The Peculiar Fate of the Missing Mate and recently reloaded the accompanying video on their Blennywatcher YouTube channel: