We hadn’t seen one of our Sharknose Goby’s for a day or so and started getting concerned that he was no longer alive. There’s quite a few places in a reef tank for a fish to hide, but it is highly unusual for our Gobies to hide, especially during feeding time. When no body was found and he did not show at feeding I started asking, “Where else could he be?”
There is an overflow box in our aquarium (as do most saltwater aquariums), which is simply a stationary box with holes at the top allowing water that rises above a certain point to overflow into the sump. Water that enters the sump gets filtered through a filter sock first, to eliminate any large bits of debris, before it gets pumped back up to the display tank. We often find amphipods in the sock when we change it every few days.
With this in mind, we decided to check the filter sock for our missing Goby, and sure enough, he was in it. We dumped him out into the sump and at first though he was dead. There is a lot water that flows through the filter sock; hundred gallons an hour, and even though the filter sock is submerged in water, I can’t image our little Goby had a easy time staying alive in there.
When we dumped him out into the sump he was not moving and he looked very grey. His normal colors are a vibrant blue, yellow and black, but within a couple of minutes he began to swim around again and his colors returned. Once he seemed back to normal we put him back into the display tank.
This led us to the question “How could he have gotten into the overflow anyway?” One options is that he jumped in. The top of the overflow box is open and rises only an inch or so above the water line so I think it is possible. However, I have yet to see any of our fish jump, especially the Gobies who are usually lounging on rocks. Another option may be that he simply fits into the overflows drainage holes. The holes are quite big and Gobies are very small fish, plus adding in their natural curiosity and you may just end up with a Goby in the filter sock. Either way, it all ended in a not-so-great escape on the Goby’s part, and a learning experience for us.