How to Identify Mooneye

To identify Mooneye (Hiodon tergisus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Silvery on the sides and belly, with a darker, often greenish-blue or olive-brown back. Fins are typically clear or dusky.

Scale type

cycloid

Mouth position

superior

Distinctive features

Very large, prominent eyes, giving it the 'mooneye' name., Deep, compressed body., A keel (sharp ridge) along the belly, extending from the pelvic fins to the anus., Dorsal fin originates behind the origin of the anal fin., No adipose fin.

Dorsal fin

Single, short-based dorsal fin with 11-12 soft rays, originating posterior to the anal fin origin.

Tail fin

Deeply forked caudal fin.

Pectoral fin

Pectoral fins are relatively small.

Distinctive fins

Pelvic fins are abdominal (located far back on the belly). Anal fin is long, with 28-31 soft rays.

Identification Tips

1. 1

   Eye Size

   The most distinguishing feature is its exceptionally large, prominent eye, which is noticeably larger than that of the similar Goldeye.

2. 2

   Dorsal Fin Position

   The dorsal fin originates distinctly behind the origin of the anal fin. In contrast, the Goldeye's dorsal fin originates anterior to or directly above the anal fin origin.

3. 3

   Ventral Keel

   Possesses a sharp, bony keel along its belly, extending from the pelvic fins to the anus. This is a shared feature with Goldeye.

4. 4

   Body Shape

   Generally deeper-bodied and more compressed than the Goldeye.

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