It is used to stop other small fish like ottos, catfish etc.. from taking all the food from your feeding as well as keeping the food in place while feeding.
**Fish line not included
1.Open the base lid
2.Fill up the cage with veggie or any shrimp food
3.Tie the cage with fish line/Cotton Line
4.Drop it into the tank
5.Tie the fish line outside the tank
6.Pull the cage out when the food is finished.