'Shark Tank' vs. 'Shark Tour' -- Allegations of Sabotage

Daymond John and Robert Herjavec, two of the money guys from “Shark Tank” are at the center of a massive $50 million lawsuit ... involving a pissed off "shark" wrangler, TMZ has learned.

A Personal Injury lawyer in Florida – Bobbie Celler – claims he hired John and Herjavec as experts to speak at an upcoming event called the "Shark Tour" -- an expo for people trying to start their own businesses.

In his lawsuit, Celler says John and Herjavec pulled out of the event just one month after they signed contracts to appear. -- and Celler says he smells something fishy.

According to the suit, filed in Florida, BC is convinced Daymond and Robert were coerced to withdraw because of “internal pressure” from Sony Pictures Television, one of the companies that produces “Shark Tank.”

Celler -- who says he's in the process of securing a trademark for Shark Tour -- suggests Sony meddled with the deal because it doesn't want anyone to think the Shark Tour is in any way affiliated with "Shark Tank."

Celler is NOT suing Daymond or Robert -- instead, he's going after Sony for tortious interference with a business relationship ... and he wants $50 mil to make things right.