Family HIODONTIDAE 



THE MOONEYE FAMILY 



The mooneyes are silvery fishes with deeply compressed bodies, small 

 heads, feeble mouths, and large eyes. They reach a length of over 12 

 inches. The dorsal and anal fins are without spines. The mouth is 

 medium sized and obliquely set and has equal jaws; the maxillary 

 bones are small. The teeth, on the jaws, tongue, vomer, palatines, and 

 pterygoids, are well developed. The gill-membranes are free from the 

 isthmus. The mooneyes have 8-10 branchiostegal rays and a straight 

 lateral line. The few gill-rakers are short and thick. The stomach is 

 horseshoe-shaped and has one pyloric caecum. The mooneyes have a 

 large air bladder. The scales are large and cycloid. The head is naked, 

 with a blunt snout. Two species are found in Minnesota and neighbor- 

 ing states. 



Key to Common Species of Family HIODONTIDAE 



Dorsal fin with 9 cIevelop>ed rays; belly keeled before and behind pelvic fins; 

 anterior margin of dorsal fin inserted just above or slightly behind anal fin. . . . 

 Goldeye, Amphiodon alosoides (Rafinesque) 



Dorsal fin with 11 or 12 developed rays; belly scarcely keeled before pelvic 



fins; anterior margin of dorsal fin inserted in front of anal fin 



Mooneye, Hiodon tergis^is LeSueur 



GENUS Hiodon LeSueur 



There are two species in this genus. Only one is found in Minnesota 

 and neighboring states; the other occurs in the southern United States. 



MOONEYE (Toothed Herring) 

 Hiodon tergisus LeSueur 



The mooneye (Figure 7) is a silvery fish with a pale olive-buff back. 

 It can be distinguished from the goldeye, or northern mooneye, by the 

 keel, or ridge, on the belly, which is developed only between the ventral 

 and anal fins. The eye is contained 3 times in the head. The maxillary 

 reaches to the center of the orbit. The dorsal fin contains 11 or 12 de- 

 veloped rays, the anal fin 28. The anterior margin of the dorsal fin is 

 inserted considerably in front of the anterior margin of the anal fin. 

 The lateral line is complete and contains about 55 scales. The moon- 

 eye reaches a length of over 12 inches. 



The common mooneye ranges from Hudson Bay to the St. Lawrence 

 and southward to Alabama and Arkansas. It is common in the Missis- 

 sippi River and its tributaries below St. Paul. It has been reported in 



