Every fish can be trained for four hours only. Though this may take time, once your fish or fishes are fully trained, you can make these pets do some of the full seven tricks that they can do inside their aquarium. Always pay attention on how you could do get through the obstacles the easiest possible way.
By the time that you are already used to the training route, you can take advantage of the 3 tries before the timer will be reset for the next 4 hours of training. It is one of the happy strategies that you can do so you can avoid doing it again and again just to get more XP (and of course coins!)
*Tip
If you would train your fishes early on, there is a big chance that you can feed those fishes more, have more XP and more coins! Everything will be two times more including the fun that you can have from them as well.