doesnt take long at all...i had a pistol in my 90 for a while before i puit in a blue fin goby, took about an hour for them to connect and start tunneling. Before the goby was added, the pistol only came out at night or for food. after the fish went in, they are out and making piles of sand every day...my pistol kills my snails and uses the shells for doors to all the burrows..