Tip 1: Reward and Praise
Training a dog or other animal isn't that different from raising a child: you have to communicate, and you have to offer lots of praise. It doesn't hurt to always be ready with a small piece of your pet's favorite treat, either.
Tip 2: Feeding Fish
Feed fish three times a day, adding only as much food as the fish can eat in a few minutes. Don't overfeed fish! You won't necessarily hurt the fish, but you will diminish the water quality of the tank.