aquariumnewbie

When the red belly piranha is still small in size like 2" or so, how do u tell the difference from a piranha and the often mistaken red belly pacu ?

Allie

The mouth is different.

aquariumnewbie

sorry to ask again. is it easy to tell when they are young and small?

Allie

Piranha have sharp teeth, the pacu had a square mouth. You have to open its mouth.

aquariumnewbie

Thanks for the info. I'll keep that in mind. although i still think i will have difficulty trying to open the small fish's mouth.

Allie

Squeeze the cheeks gently...it is difficult but the difference is obvious

aquariumnewbie

I also realized that the mouth & head shape and the tail have differences too. Is it easy to look and identify the fish by looking at the shape of the head and mouth and the tail? I realize that there is more of a V shape in the pacu.

Allie

There probably is, b/c they really don't look much alike when grown.

aquariumnewbie

thats true. i've seen pictures of them when they are grown. but what the LFS is selling which i don't know whether is it real piranha or just a look alike , the size of the fish is quite small and hard to tell the different. so just trying to gather more info on how to identify them when they are small in size. tough thing to do.... =/

RiffDawg15

A pacu's eyes are a bit bigger and stick out of the head farther. Also the mouth and teeth are different.

Red belly piranha have smaller eyes and they dont stick out of their head as far as the pacu. Also they have a more rounded mouth.