This species differs from E. electricus by having a ventral outline of head ovoid, widest anterior to branchial opening (vs. U-shaped) and with 112-146 lateral-line pores (vs. 88-101); differs from E. varii by having the skull depressed (vs. deep), cleithrum lies between vertebrae 5 and 6 (vs. between vertebrae 1 and 2), wide head (vs. narrow); distance between medial margins of contralateral dentaries at transverse through last two ventral pores 2-3 times longer in E. voltai than E. varii; low-voltage electric organ discharges or EOD duration 1.72 ms; high-voltage EOD 860 V at 121.9 cm TL (Ref. 120918).