how big or small is the fish
this worked for me i got a coke bottle or water bottle based on how big the fish was.
cut it in about half, cut it once the bottle is the same size tube. like right under the part you pour outa. then flip it around and put it into the other half so that the part you pour outa is faced towards the bottom of the bottle. then put in water with alil food in it and wait.
worked for me but took about a week to finally get him.