It takes along time for people to become accustomed to caring for Pacu. We have listed a few suggestions that we would have liked to know when we were first time Pacu owners.

1. If you are going to buy Pacu, make sure you are committed to providing ample room for growth. They will need a 250 gallon tank at some point.
2. Only buy one or two pacu. When they are large they eat a lot and it is very difficult to keep the tank. Also, more fish means more room needed.
3. Make sure you understand what kind of tank mates pacu may have. They will either out-grow your other fish and eat them or they will fight for territory.
4. Add some salt. To make sure it is the right amount contact your pet store. I use 1 Tablespoon per 5 gallons. I also make sure to account for evaporation.
5. Clean the tank often. Again contact your pet store to know how often to clean the tank.
6. Feed your pacu when the lights are off. They are more relaxed when the tank glass acts as a mirror and they are not threatened by outside elements. The are more fun to watch.
7. Document your pacu's growth in writing and with photos. They grow so fast they are fun to watch and monitor. Sometimes they grow so fast that I think that I can note differences in size from day to day.
8. Feed your pacu the correct diet. Many believe they eat only a certain thing. I believe that they will eat pretty much anything they can consume if they are trained to eat it. They do require a specific diet for their best health. Talk to your pet store for their diet. I feed mine a combo of siclid sticks, flakes, greens (lettuce and peas) and an occasional feeder gold fish.
9. Don't put metals, soaps (careful how you wash your hands before you put them in the tank), or any other chemicals in the tank unless they belong there.
10. When feeding your pacu, turn on the lights in the tank and turn off the lights in the room they are in.
11. Place a rock or something in the tank so your pacu can duck away when they are frightened. They will not bang on the glass as much if they know there is a place larger than they are to escape to.
12. As the fish get bigger it is very important to change the filters frequently.
13. Be very careful of the type of water heater you have. Either try to protect it with a rock or branch or some other type of shield because the fish can break them. Please see the Pacu Facts link above and go to the topic Experienced: Watch out for the water heater. 
14. Have fun with your pacu fish. They are beautiful and set a scene of peace and serenity in the home. Enjoy em.