@Lightlyseared While many chordates are vertebrate, not all are, and certainly not all vertebrate are chordates. Here’s what distinguishes the chordata from other phyla.
Here’s what I was able to find.
“Believe it or not, whether fish suffer flatulence is an ongoing debate among ichthyologists.
“True farting is a by-product of digestion, and some experts say that the digestive gases of fish are consolidated with their feces and expelled in gelatinous tubes (which fish then eat!) ...” http://www.physicsforums.com/showthread.php?t=72695