Aquarium-hardy Michigan Fishes 



THE LAMPREYS 

 (Petromyzonidae) 



Lampreys are brown, scaleless, eel-like fishes without paired fins and 

 with circular, sucking mouths armed with rasping teeth. All but a 

 few of the brook lampreys are parasitic upon other fishes at one 

 stage in their life history. When sexual maturity is reached these 

 lampreys stop eating. Eggs and sperm are developed at the expense 

 of the organs of digestion, which almost totally disappear. This 

 development takes place in the fall, but spawning takes place in 

 the following spring, in the swift water of streams. Spawning is a 

 communal affair. Several individuals carry stones from gravel beds 

 to make a nest. After spawning the adults invariably die. They are 

 replaced by little blind, toothless larvae, with horseshoe-shaped 

 mouths, which hatch from the eggs, burrow into the mud of the 

 stream bottom and live there like worms for at least three years 

 before they transform into adults, to complete the life cycle. 



American Brook Lamprey 

 (Entosphenus lainottenii) 



Appearance. Adults: mottled blackish and chestnut brown, scale- 

 less, eel-like, with a circular mouth armed with rasping teeth. 

 Larvae: dark brown, wormlike, with a small tail fin. 



Size. Adults: 150-250 mm. long. Larvae: from about 3 mm. 

 to adult length. 



