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Seeking the truth About the Feared Piranha
ARTICLE AND *PHOTOGRAPHS BY
PAUL A. ZAHL, Ph.D.
SENIOR NATURAL SCIENTIST

(*) Unless otherwise noted

I STOOD AT THE EDGE of a shrunken lagoon in southern Paraguay. It was the peak of the dry season, and the water was low and mirror still, save for an expanding circle here and there caused by the touch of a dragonfly or the surfacing of a small fish.

Opening my fishing kit, I tied a steel leader to the end of a 20-pound-test line, then a hook. My knife sliced a cube of bait from a hunk of sinewy local beef. My rod was a branch trimmed from a nearby thicket.

Unseen in these sullen waters swam piranhas – hungry, as are all fish, but allegedly a hundred more times more rapacious, attracted to anything fleshy, I had read, like iron filings drawn to a magnet.

I had heard of the proverbial horror stories: the canoeist suddenly minus a finger; the cow skeletonized while fording a stream; the swimmer disemboweled by sudden attack. Nineteenth-century naturalist Alexander Von Humboldt referred to the piranha as one of South America’s greatest scourges. The words of eminent ichthyologist Dr. George S. Myers also came to mind: "teeth so sharp and jaws so strong that it can chop out a piece of flesh from a man or an alligator as neatly as a razor, or clip off a finger or toe, bone and all, with the dispatch of a meat cleaver."

Paraguay example of P. nattereri. Credits on photo.Rapacious killers or creatures much maligned? In an attempt to separate fact from fancy, the author journeyed across South America studying piranhas, including Serrasalmus nattereri, considered the most dangerous. These Brazilian specimens have red undersides  while a Paraquayan example inspected by Dr. Zahl (PHOTO LEFT), has a yellow belly. (Due to copyright I have substituted an image of the same colored species now placed as Pygocentrus nattereri).

On the other hand, during repeated visits to, South American hinterlands, I had also watched Indian children splashing carefree and unharmed in piranha-inhabited waters (pages 720-21), their mothers waist-deep nearby rinsing laundry. Brazilian anthropologist Harald Schultz, after spending more than two decades in piranha country, could write, "In all these years I have never had a harmful experience with these greatly feared piranhas."

Unspectacular – Except for Its Teeth

Mindful of both sides of the story, I stitched the juicy bait onto my hook and swung the line out over the lagoon. In a few seconds I felt a tug. I braced and whipped up the pole. It was disappointingly easy. Onto the bank flew a silvery fish scarcely larger than my hand?a little creature no more impressive than the trout of my boyhood days in the Sierra Nevada. But the comparisons stopped when I caught sight of jaws snapping wildly in their effort to dislodge the hook. Had my leader not been steel, it could have been severed instantly. "Don’t touch him!" warned my companion, Senior Juan Pio Rivaldi Blanco, chief of Paraguay’s Fish and Game, and Fish Breeding Division. His boot came down, pinning the flapping piranha to the ground. Cautiously he removed the hook, seized the fish behind the gills, and held it up. Latinized as Serrasalmus nattereri, this struggling specimen had silvery sides and a yellow belly– quite unspectacular, except for that mouthful of fiendish teeth. Each was a razor-keen triangle set so that when its cutting edges met those of opposing teeth, the shearing power would be all but irresistible (pages 722-3). About a score of piranha species, differing in head shape, coloration, size, and temperament, but nearly all possessing that incisive bite, claim a habitat covering some four million square miles of tropical South America. They are found wherever fresh water flows or stands– from the lower eastern slopes of the Andes through Colombia, Venezuela, and the Guianas; south and eastward across the immense Amazon Basin; into Bolivia, parts of Peru, Paraguay, Uruguay, and northeastern Argentina (map, page 719). Known as perai in parts of the Guianas and caribes in several other lands, they take their more common name from dialects of the Tupi linguistic group, in which, pira means "fish" and ranha "tooth." Virtually all piranhas belong to the genus Serrasalmus of the family Characidae, which also includes many a good-tempered aquarium fish. One of the smaller piranhas, Serrasalmus spilopleura, reaches only about half the length of the big dark Serrasalmus niger, which may grow as long as 18 inches and weigh as much as five pounds. In my experience, the little one was not dangerous; I had encountered it everywhere in Paraguay, even in the smallest streams. Serrasalmus niger was another matter; while some of my informants declared it to be among the most harmless, others gave it a dangerous label. All my experts agreed as to the peril of dealing with Serrasalmus nattereri, the species that is probably most responsible for the piranha’s fearsome reputation. Some species have a tendency to gather in schools, while others are loners, except when lured into a group by the smell or taste of blood or raw flesh. Some are said to prefer deep habitats; others seem to frequent the shallows, either turbid or clear. Certain species appear to seek quiet waters, others the more rapid currents. Some seem savage; others are only moderately aggressive. Some seem to be omnivorous, but most are basically flesh eaters with cannibal tendencies.

Opinion Changes in a Split Second

To observe and photograph piranhas in their natural habitats, I planned trips that would sample the group’s entire geographical range. I would begin along the Paraguay-Argentina border, then move northward into Brazil, proceeding eventually into the heartland and the delta islands of the Amazon, and as far north as Surinam. My finding Serrasalmus spilopleura – the small innocent one– abundant in Paraguay, I was lulled in my estimate of the piranha potential. I had often picked this fellow from a net by hand, finding him no more hostile than a goldfish. Then one day an eyewitness experience changed my outlook. Driving through Paraguay’s picturesque cattle country a hundred miles south of the capital city of Asuncion, Senior Rivaldi and I drew up to an isolated and brooding lagoon. Six or seven fishermen, hip-deep in the water, were setting a long seine. I approached the net’s onshore anchor man, clad like the others only in shorts and straw hat.

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