Well think about it a bit before you decide whether this is inhumane or
not. How much space do these guys actually have? Well according to the
link you provided the smallest available ecosphere is 3.25" now I don't
know exactly how big the creatures inside are but for simplicity lets
say they're 1/2 an inch long. Sound reasonable? Well then that means
that the diameter of their world is 6.5 times longer than they are.

Now lets think about a full grown Oscar in an aquarium. Lets assume
this fish is a foot long - that's reasonable. Now, for it to have as
much living space as these shrimp it will need a 6.5 foot diameter
tank. How many full grown Oscar owners out there have a tank with a
single 6.5 foot dimension - let alone a 6.5 foot diameter sphere's
worth of living space?

We keep fish in much smaller areas than these guys are being kept in,
relatively speaking. It is probably much more humane than many of the
things we do every day and think of as good practice. I think the
spheres are a neat idea.

-Daniel