I have a bumblebee goby (99% certain it's xanthozona, instead of nunus, etc., perfect stripes rather than broken lines or spots and doing fabulously in freshwater).
A lot of what I read says bumblebee gobies will spend the majority of their time hiding. When I first got my bee (close to a month ago) that's what he did. I only have one because he was the only one left. For the first couple weeks he just hid competely out of sight. Like hid so well I had to move decorations to check on whether he was still alive or not. Well his only tankmate at the time was an Apple Snail
(mystery snail...whatever name you prefer
) and his black/yellow stripes were faded to a depressing gray even though he wasn't sick and didn't have any parasites. I recently added 3 habrosus cory cats and since then his color has stayed vibrant, typical bold bumblebee stripes, and he peruses all over the tank. He even seems to have established a territory now--an egg-shaped rock he likes to sit right on top of, or in the shadow of, and he almost never hides completely out of sight anymore (like he used to when he was inactive and ... sulking?) Anyway what I keep meaning to ask about is: While he often swims all over the tank he spends most of his time going up and down the right side of the tank glass, closest to his favorite rock. I know sometimes when fish do certain things (hang out near the surface...lay on the bottom...etc.) it's a sign they may be sick, the water's bad, on and on, but my water is fine, crystal clear & dechlorinated, 25% water changes pretty frequently (not enough to keep the tank from cycling though), there's a soft current, between 75-80 (F). Is this up & down swimming (near what I assume he's decided is his "territory") common in bumblebee gobies, or in territorial fish in general? Remember he only started doing it after I added the 3 habrosus cories, which he gets along with fine otherwise (the three cories normally hang out together, but occasionally 1 will break away and swim up and down with the goby, LOL too cute).
Unless anyone has specific reason to believe it's a warning sign that something's wrong, I'm not going to change anything. Before this he was lethargic and pale. Now he's bright, shiny and eats like a pit bull. But I thought I'd run it by a few experienced persons because any sudden change in any pet I figure should be closely examined.