'Thicker Than Water' Star Brooklyn Tankard -- ARRESTED For Turning Her Kid Into a Truant

Brooklyn Tankard -- one of the stars of Bravo's "Thicker than Water" -- won't be winning any Mom of the Year awards ... she just got popped for allowing her kid to skip school.

Tankard -- known as "Queen Brooklyn" on the show -- was stopped by cops in Murfreesboro, Tennessee for a traffic offense ... and a license check turned up some outstanding warrants ... including one for "Failure to Cause Child to Attend School."

According to court docs ... Tankard's 10-year-old daughter, Diamond, had 16 unexcused absences from school ... and had another 35 unexcused tardies.

So they arrested Brooklyn for not forcing her kid to go to school.