It's easy: text 30644 with the message FISH and the name of the fish in question. Within a few seconds, you'll get a text back with Blue Ocean's current assessment and better alternatives to fish with significant environmental concerns.
I just tried Monkfish and got the following:
"monkfish; (YELLOW) some environmental concerns; try farmed rainbow trout, or U.S. farmed tilapia instead."
Okay, so it's not terribly detailed, but still informative. When you get home you can kick back and read the full report (here's monkfish).
(Monkfish photo at left by Robert Shetterly ©Blue Ocean Institute)