title: Positioning of turtles
body: <p><a href="https://i.stack.imgur.com/8WIDU.jpg" rel="nofollow noreferrer">Fishes and planktons</a></p>
  
  <p>Hello! This is a 20x20 worls. Currently my program randomizes these planktons (green grass) and these fishes (orange fish). What I would like to do is to place all the planktons in just a certain portion of the world, say the lower left part, what should be my setxy?</p>