The Pacu fish (right) looks like a Piranha (left) but lacks sharp teeth and prefers to live on fruit instead of flesh. The Pacu will wait until the Amazon floods, and then it will swim among the flooded fruit trees, eating the ripe fruit that has fallen into the water. These fruit are rich in fructose, and the Pacu gains a lot of body and liver fat, much like animals preparing for hibernation. As the Amazon recedes back to its original size, the Pacu will often go weeks to months without eating, living off the fat it accumulates.
- Johnson, R.J. (2012). The Fat Switch. Hoffman Estates, mercola.com.