Reading pair Sean Morrison and Jordan Obita have both signed new contracts at the Madejski Stadium.
Ipswich defender Aaron Cresswell has signed a two-year extension to his contract.
Former Tottenham and Middlesbrough forward Mido, 29, has struggled for full fitness and has only made one appearance for the Tykes since arriving in the summer
Collins has not appeared for the first team at Barnsley this season following his arrival from Port Vale, initially on loan in March last year.
The 24-year-old, who started his career at Wolves, made over 130 appearances for Port Vale during a two-and-a-half year spell with the club before arriving at Oakwell.
He made seven first-team appearances last season.