Oh... this write-up about the Bumble-Bee Goby is sooooo
amusing!!
"Bumblebee gobies are grumpy. They will not school with other
species of fish easily, if ever. Their faces seem to give them
away, with their permanent frown and drooping corners to their
mouths.
"If bumblebee gobies were homeowners, they would be the type
that cut only their side of the hedge, and would daily measure
their borders just to make sure that their land stayed their own.
They are highly territorial, but are prone to frequently move house
too, never really approving of their neighbors. If you keep
bumblebee gobies and see them randomly fighting, they are
attempting to set up borders of a territory, and it's little to
worry about; damage is very seldom done if they are not
overstocked.
"Feeding can be quite a chore. Because they are ambush
predators, preferring the "wait until it floats right past" method
of hunting, they can be difficult to feed with frozen foods, and
practically impossible to feed with dried or flake foods.
Orh... so for the first week or two, they pretend to be
'friendly' and harmless to the shrimps so when the shrimps drop
their guard, they ambushed one and made a snack out of it!

The gobies are soooooo like some of the people we know!
The act-sweet, "I
just wanna be your friend" aka "I care about you, really" type who
are just using their fake-as(s) facade to try and trick you into
becoming comfortable with them so when you least expect it, they
will get what they want out of you and suck you dry!

But when they attack, they make sure that it's as stealthy as
possible so that the others are none the wiser about their dark
side so that someday in future, they can makan on the others
too. 
Maybe that's why sometimes, I see the gobies doing some strange
'head-on collision' thing with the tetras when they were all in the
tiny tank. Boy, am I glad I got a much larger tank so
everyone can flee and hide!!!

Bumble Bee Gobies