Don't have to wait for fish to have babies, or grow up
Go to the DS main menu then go to the little DS at the bottom of the screen then go to the clock Icon. After you click on that you can ether set the alarm,clock or the date but dont set the alarm set the clock or calender clock for babies and calender for age but I would recomend the clock for the age.
Selling faster
Always set the speed on 2X. If you do not do this, you will probably have to wait for hours to sell something at a high price.