Gouldingi's are rare but not very very hard to find. They are new discovered species, first found in 1992... It is 2 inches I think one on the pic...I cant find any in the net to see how much others charge
Here is some info on them
new species of piranha in the genus Serrasalmus is described from the Rio ***** and the Rio Japur, of Brazil, and a tributary of the Rio Casiquiare of Venezuela. Serrasalmus gouldingi is a serrasalmin unique in having the following combination of features: proximal black band on caudal fin, vertically elongated stripes on the lateral body, and no prominent vertical humeral blotch. Fink and Machado-Allison 1992).
This species is different from the rest of the genus Serrasalmus from Venezuela by having a very pronounced, large rhomboid body. Very robust head and bulldog-like mouth, large eyes, pungnacious lower jaw. The ectopterygoid teeth are few in number (1-3) variable ontogenetically. The base of the dorsal fin is moderate with 2, 14-16 branched rays. The preanal spine is present. Vertebrate 37-38, usually 38. Numerous small scales. Lateral line 93-97, usually 95. Prepelvic serrae 24-25, postpelvic 8-10. Branched spines are shot the base wide, 23-27, usually 25.
The flank of the fish is silver with bluish metallic iridescence, often with dark pigmentation along the border of the infraorbital (gill edge). The eye color is metallic blue with a dark vertical band transecting the pupil and orbit of the eye. During ontogeny the eye color progresses from metallic blue to copper (brown with a tinge of red) to black. The dorsal and posterior of the head, mouth and part of the lower mandible is black. Some examples have pigmentation in the humeral area. The dorsal fin, anal, caudal and adipose fin are tinted (dark). The caudal fin has a dark border and the posterior hyaline (like a dark "V"). In juveniles, the fins are generally hyaline except the base of the caudal. In adult examples during reproduction, the body is very dark with a coppery tone (brownish with tint of red). The ovals (elongated body spots) are very evident on preserved juveniles, but inconspicuous on live specimens, with the exception of very small juveniles.
In comparison with S. manueli, S. gouldingi humeral blemish is much smaller and does not extend as far as S. manueli. The body of S. gouldingi is much deeper than S. manueli or S. rhombeus.