Man Served Black Eye During Wild Frontier Airlines Altercation

A New Jersey man was met with a swift dose of karma to the face on his recent Florida-bound Frontier Airlines flight after allegedly attacking another passenger ... for absolutely no reason.

Part of the wild altercation was caught on video ... and it shows 21-year-old Ishaan Sharma in a physical struggle with the passenger behind him as onlookers urge the men to cut it out. Once the travelers cool off ... Sharma packs up his belongings like nothing even happened!

But the shiner on his face tells another story -- just check out the booking photo TMZ obtained from the Miami-Dade Sheriff’s Office ... Sharma's left eye is swollen and bruised, and there are several lacerations on his neck and next to his eye.

Police say Sharma allegedly grabbed the victim by the neck -- fully unprovoked -- as the victim was heading back to his seat ... after which, a physical altercation ensued.

The victim -- reportedly Keanu Evans -- walked away with only minor cuts. Sharma, on the other hand, was cuffed and taken to the hospital by Miami-Dade law enforcement ... and then locked up behind bars Tuesday once he was cleared.

He's currently in a cell at Turner Guilford Knight Correctional Center in Miami-Dade County and charged with battery. He has not yet satisfied his $500 bond.

Sharma's attorney Renee Gordon claimed the fight occurred due to the victim taking issue with Sharma's meditation practices, according to the Daily Mail.

Evans had a completely different idea in mind of what went down, telling WSVN Sharma was the aggressor from the get-go.

He claimed ... "He was doing some, like, dark laugh like, 'ha ha ha ha ha.' And he was saying things like, 'you, you puny mortal man, if you challenge me, it will result in your death.'"

Evans further alleged Sharma threatened "me with death" multiple times. He reacted by calling over a flight attendant ... and he says things hit the fan from there.