Mark William Bluett, 20, of Invermay, his father Derek William Bluett, 47, of Deddington, brother Daniel James Bluett, 18, of Blessington, and Matthew Jordan Crawford, 20, of South Launceston, pleaded guilty to assaulting staff at the Newstead Hotel in October.

The court heard the defendants, except Crawford, had been at a relative's funeral that day and, according to lawyer Fran McCracken, were being provoked by another bar patron.

A fight erupted when the father began punching the hotel bouncers, triggering his son's involvement.

Mark Bluett, who punched a bouncer in the head several times, has previously fought bouts in the Tasmanian MMA competition Valor.

The organisation has previously taken a dim view of violence outside the ring.

Crawford, who threw a bar stool hitting the barman's back, was deemed to be the least culpable and was not convicted.

CCTV footage of the incident was played to magistrate Tim Hill on Wednesday.

"This sort of violent behaviour simply cannot be tolerated in a civilised society," he said in the Launceston Magistrates Court yesterday.

However, he accepted "it would have been a very emotional time".

None of the victims received lasting physical injuries.

Daniel Bluett was fined $750 while his father, who received a wholly suspended jail term for assault in 2001, was fined $1600.