Learn Bisaya Cebuano

Verb roots and stems.
Palit and papalit.
Clarification:
Gipapalit ni Manny ang isda.
Manny bought THE FISH (because he was told to, or something happened that made him do the action).
How would you say:
THEY will buy this fish.
(They will have someone else buy)
THEY will buy this fish.
(Someone told/texted them to buy)
They will buy THIS FISH.
(Someone told them to buy this specific fish)