Here is some advice on how to get the God achievement in the bait master mini-game.
1. Position your pygmys well. The position of your pygmys is vital if you are trying to get a high score here. A good strategy is to position them in sets of 3. 3 on the left, and 3 on the right, and spread them out so that one is up top, one is in the middle, and on is at the bottom. That way wherever a piranha is coming from, he's gonna get fed, and fast. There are many other ways to position the pygmys, but this is the way I do it. Different ways could work for you, but whatever you do, don't clump them all in the middle of the screen!
2. Make sure that you watch your piranha as he's leaving the screen as well. The piranhas can fight even if only half of there body is on the screen, so watch where the arrows appear, and draw a line for your piranha to exit, away from that arrow!
3. Always keep 6 pygmys on the screen! If you have 6 pygmys on the screen at the same time, you have more "meals" for the hungry piranhas to go to. This shouldn't be your main focus, but you should never forget to click that "+" button as many times as you can.
4. Things speed up pretty quick after 50, so make sure you keep an eye out for the piranhas coming in, the ones leaving, and the ones eating. Try and draw longer paths sometimes for your piranha, so it detours before eating, and that way it can escape from fighting other piranhas. :)