This is story about a fruit loving fish called The Pacu. What?! Yes, have a read.
Aren’t fruits yummy? Don’t get me wrong, vegetables are nice, but turnip and spinach are rather boring when compared to a sweet, juicy, deep-red raspberry. Everything about fruits scream “eat me!”, as if they come straight out of Alice in Wonderland.
There is a reason for it. Plants want you to eat their fruit. They need it for seed dispersal. The proverb is wrong: an apple want to fall as far from the tree as possible. The chance that an apple seed can survive in its mother’s shade is very small. The best way to get away from it, is by being as attractive as possible for a passing wild boar. The animal eats the entire fruit, and after several hours in the digestive tract, the seed is dropped somewhere far away, along with a bit of manure.
Birds and mammals are usually chosen for this job. A fish seems a less likely candidate. But for one third of the palms and trees in the Amazonian varzea and igapó forests, it’s the preferred transporter. The pacu is a big fish: the largest species, the tambaqui, can weigh more than 30 kilograms. It’s a relative of the piranha, but unlike its bloodthirsty family member, the pacu is entirely frugivorous. Its strong jaws are used for cracking nuts only.
For a large part of the year, the pacu has limited access to these fruits and has to rely on its fat reserves. But in the rainy season, the river level rises, flooding the open forests on its banks. The forest is now taken over by fish, otters and other water creatures, even river dolphins!
During this season the trees produce the most fruits. Underneath the fruiting tree, the pacu awaits. The fish is attracted to the sound of fruit plunging in the water, something that fishermen have learned to take advantage of. At the end of the flood season, the fish has eaten its belly full and can survive times of scarcity.
For the trees this is also beneficial, as not every seed is crushed and has a good chance to get excreted. The bigger the fish, the more seeds are swallowed whole. When the water recedes, enough seeds have found the perfect place to germinate. It shows how delicately intertwined ecosystems are. Sometimes even the most unlikely partners depend on each other for survival.