Almost all characins have teeth in the mouth and some tetra, like the Emperor tetra, (picture above by Hristo Hristov) when seen close up, are easily comparable to the piranha of this same family. ... They are often recognised as the jutting tusk-like teeth on fish like the Tiger fish (Hydrocynus).

Are tetras related to piranhas?

Piranhas are shoaling fish that belong to the family Serrasalmidae. They are related to pacu, silver dollars and tetras. There is some debate as to how many different species there are, but it is thought to be somewhere between 20 and 50.

Do tetras bite humans?

Tetras feature highly on the nipper roll of dishonour, with Blue emperor tetras (like the badly nipped specimen pictured above) Blue tetras, White spot tetras, Buenos Aires tetras, Blind cave fish and Black widows all known to have a bite or two in them.