The Nicks are our paired Yellow Watchman Goby (Nick Snider) and Tiger Pistol Shrimp (Nick Sniderer). I don’t know if this could be called a “bond” or not since I have no idea if they care about each other in particular. What they do do is share a large system of tunnels. The pistol shrimp is a proficient digger, even being capable of digging through rock. When he’s working on that it’s quite audible if you’re in the same room, causing a noticeable popping sound.
He shares his space with the Yellow Watchman due to his bad eyesight. The Yellow Watchman has excellent vision and likes living in tunnels like what the Pistol Shrimp digs. In return he’ll stand guard when the pistol is outside of the tunnels. They maintain communication by the pistol shrimp keeping one antennae on the goby. When the pistol shrimp wants to do something outside of the den the goby will accompany him, staying close enough to stay in contact.
Remarkably (to me at least), the Pistol Shrimp seems to have basic knowledge about how to reinforce tunnels. He regularly goes exploring for shells, or small rocks in the sand and drags them back into the tunnels. Unfortunately his constant digging is disruptive to the aquascape, meaning that all immobile additions need to be placed in areas that he’s unlikely to bury. The rocks themselves are largely either sitting on the glass or are stacked on other rocks. This also means that certain corals, which would be better placed on the sandbed, need to instead be on the rock. If they aren’t, he’ll tunnel underneath them and knock them over or just bury them.
These two are a piece of cake to feed. I pretty much don’t need to. The Yellow Watchman is a sand sifter, though he prefers to eat meat if available. He scoops up a mouthful of sand, chews it a bit, and then pushes it back out through his gills; filtering out edible debris and copepods along the way. The Pistol Shrimp is a scavenger but is also happy to hunt smaller invertebrates. Even if he can’t find enough to eat, he can always hunt for it!