How long will it take for it to become normal
It has only been 8 days since you started this thread. Probably by the time he is 18 - 20" he will have outgrown his shyness. Our pacu were already 15" when they joined our family. They were not shy.
by the way, which types of fruits and veggies
People feed their pacu just about any fruit and vegetables - grapes, potato.... They are very messy eaters, and the water can quickly become full of food debris (which is why I quit feeding mine this way) Nuts. I fed my pacu almonds, but they inhaled the almonds without chewing. I was afraid that my mechanical filtration plumbing might get jammed up if the almonds were not digested, so quit feeding them almonds. One time I fed them unlimited amounts of watermelon and had an ammonia reading in the water, so quit doing that. Water quality is extremely important for pacu. They are more sensitive to nitrogen products than their counterparts in the wild. I do enough water changes every day to keep nitrates below 5ppm. Watching pacu eat is extremely entertaining for us. Water quality issues made us switch to sinking veggie pellets where there is no mess in the water after they eat.
Here are some very old videos of our pacu eating. You can see the water quality is terrible after they eat with food debris everywhere. All of that debris will result in increased nitrates.
Eating potato chips (slices of raw potato) notice all the potato debris in the water. Leonardo nips at Adonis' tail, causing Adonis to swallow and get his potato stuck in his mouth. When he tries to pick up his last slice, he is unable to pick it up with the potato still in his mouth. Leonardo gets the last piece and grins as he polishes it off.
Pacu tag team a whole carrot
End of the carrot - there is also a big piece of brocholi in the water
I did a comparison of different fish food. Even the pond pellets have adequate nutrition for pacu, except that they float. If you have overflow boxes and sump filtration, this might become problematic with the floating food entering the overflow boxes and filtration (it did for us, which is why we switched to sinking food) I would not feed the game fish chow or the Massivore. I put those in just for comparison.
