It may be found in the main courses and streams, as well as in lakes and lagoons; it often shelters among stones and aquatic vegetation.

Megaleporinus obtusidens has an elongated wide body, with a comparatively small head and a blunt mouth; its teeth are reminiscent of the incisors of Lagomorpha, whence the name of the genus (leporinus, "hare-like", as in Leporidae).

Its basic colour is a light greenish-gray, with three rounded dark spots in mid-flank, which may not be visible in some specimens.

In young individuals there are also eight broad vertical streaks, joined in the back and coming down to the middle line.

The length and weight of the individuals are extremely variable according to the area, probably influenced by different feeding habits, opportunities and exploitation, as well as local sub-specific variants.