The Argentine has signed a five-year contract and Deportivo have claimed the final fee for the 26-year-old Argentine, who played in all La Liga games last season, could rise to £10.3m.
"Fabricio has got tremendous experience and is a full international with Argentina, that tells you he is a player of the very highest calibre.
"He does not know the Premier League but he knows world football and has played in one of the top leagues, La Liga, for six years now.
"He's a very athletic player, he played every minute in the league for his club last season, and he's also very versatile.
"He is a centre-back but can play anywhere across the back four and also in midfield - he gives us massive options."
And, when asked if the real reason behind Coloccini's arrival was the defender's 80s-like perm akin to that sported by the likes of himself and Terry McDermott, the boss quipped: "A few of the lads have already said that me and Terry want to revive the perm, but as long as this lad can play we're not bothered what his hair is like!"