I've had mine for a couple of years and he has gotten more attention than any other fish in my entire aquarium keeping hobby. Here is what I've learned.. if your experience says anything different, don't get mad at me for my particular experience with this species of fish.
1. They dislike being in a community tank. They will get friendly with their owners but will hate having different fish swimming around them.. if you keep them alone, eventually they will come to the top and want to be hand fed. Mine would stick his head out of the water with his mouth open waiting for me to drop food in.. they can survive in a community tank but if they are spending even 10% of their time hiding, they aren't feeling as secure as they could.
2. They are tolerant of bad water parameters. These fish are use to horrid water quality in near-swamps. It doesn't mean it's good for them but I've not found another fish that does better in bad water. Death in the family, 6 months with no water change and him and a striped raphael were all that was left. He doubled in size.. he's actually a bit less perky and comfortable since I fixed my community tank and turned it into a 0 nitrate tank.
3. They are scavengers and filter feeders in their natural habitat. They can and will eat anything you throw at them and they will grow and be healthy and happy having it. I would say my Goby's staple are shrimp pellets.. but he eats anything from plant trimmings to fish waste (I dont feed him this stuff, he just eats it). Cut shrimp, squid, shellfish and some cheap whitefish. Flakes, algae tabs, true vegie tabs. Ghost shrimp, Redworms, earthworms, mealworms, etc. It doesn't matter, if it can be considered food they can thrive on it. Over the years I've noticed mine seems to be happier with a varied diet so I just throw him whatever I have..
I caught him eating a rosy red my needlefish had killed but missed the other day, it was too big for him to swollow so I cut it up (never done this before) and he loved it.
4. They are peaceful fish, however, they do not like having to compete for a place to hide. Their teeth can be a bit on the sharp side and enough to hurt many scaleless or smaller fish, be careful of this.
5. They dig. If they cant' dig, they will be unhappy. Simply having a cave or a pipe for it to hide in will do but when they get older they prefer having places to dig under something.
6. They, at most, will grow to 20'' in a home aquarium. I've never seen one bigger.. mine is a couple of years old, well passed maturity and he's considerably smaller than 20''.
7. They don't need anything more than a 20 long if you're housing them by themselves. Bigger tanks are always better for fish like this but they would rather pick a single, secure spot and not move from it. Trust me when I say a 20 long with a full grown Goby by himself is 100x's better than having a full grown Goby in a 75G community.
They're like eels in the way they can flex, mine has never had trouble with space in a packed 55. In fact, I'm moving him to a 29 so he has some more space to move around in and I imagine he'll love it.
8. Mine has almost always been kept in freshwater and it is perfectly healthy. I'd say they're like Mollies in their tolerance for fresh.
9. They are pretty dumb fish and are almost blind. They *need* special attention. You have to make sure food gets to them, they can't compete for it. You have to make sure they have nothing in the tank that can hurt them (Mine lost one of his eyes trying to squeeze into a spot in my tank), including other fish (I had a nasty ZigZag Eel that was trying to pick at the gills of my goby, it would just sit there and let it).
They are a high maintanance fish. The bigger ones put a huge bioload on your tank, they're destructive to decorations and they have little trouble getting out of tanks if they really want to. They have surprisingly small stomachs for their size and have trouble eating larger pieces of food but they will try.
You will notice yours expelling food and rocks all the time, keep an eye out because they can occasionally get something stuck in their throat. I had to remove a piece of broken off driftwood from my Gobie's throat with tweezers a few months ago..