Guentherus is a genus of jellynose fishes, belonging to the Ateleopodidae family, with two recognized species:

• Guentherus altivela Osório, 1917 (jellynose, highfin tadpole fish)
• Guentherus katoi Senou, Kuwayama & Hirate, 2008

The genus distinguishes itself from others in its family because of discrepancies in morphology. Guentherus has "3 free rays followed by 6–9 normal rays with membrane between them in the pelvic fins." Other genera in this family have "a single long filament or 1 relatively developed ray plus 0 to 3 rudimentary rays."

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