Who actually coined this phrase isn't very clear, but that doesn't take away from its meaning and impact. Often times people give "go with the flow" as advice, and in some situations, this may be truly helpful. For example, while you're driving you definitely want to go with the flow, because if you were driving against the flow you would likely have a head-on collision. This doesn't make you a dead fish, in fact, it does the quite the opposite.
Obviously the phrase is not intended for driving, so what does it mean? Well, let's look at the phrase "go with the flow" first. People who 'go with the flow' do what everyone else is doing, they wear what everyone else is wearing, have what everyone else has, does what everyone else does, eats what everyone else eats, says what everyone else is saying and thinks what everyone else is thinking.
That last part is what frightens me about people going with the flow. Do not allow others to think for you, even a large collective of others. Each person should think for themselves and therefore become incredibly individualistic. Wearing unique clothing, saying their own words, thinking their own thoughts and arriving at their own conclusions. So what's a dead fish? Well for one it's dead, and for the other, it's a fish. So a dead fish wouldn't really do much besides be eaten by other, living fish and float along downstream.
Don't be a dead fish -- ignore the flow.
Conformity has become a real problem lately. Everyone else my age is voting for Bernie Sanders so I should too, everyone else has a smartphone so I should too, everyone else posts corny captions with their pictures on social media so I should too, everyone else plays sports so I should too, everyone else writes Odyssey articles about stupid stuff like "5 Things My Daddy Spoiled Me With" or "The Top 10 Places You'll Go If You're Hipster" or "7 Things You'll Remember If You Went To this High School That's Ranked Really High, Even Though I Didn't Try Because I Was More Concerned With Who Josh Was Taking To Prom Than My Chemistry Grade," so I should write those kinds of articles too.
I have not written typical articles, which have given Odyssey the reputation it has among many 20-year-old cynics, and I have still done well once or twice. You don't have to conform to succeed. In fact, the true leaders we look back on in history as influential and great are the ones who were revolutionary and conformed to no one. Martin Luther King Jr. explicitly disobeyed the status quo, George Washington lead a rebellion against his government and perhaps the greatest rebel of all time was Jesus Christ who refused to bend to anyone else's will so that he could teach them to love each other. Don't be another face in the crowd -- be a living fish.