95 



Western black-noted dace 



Western black-nosed dace 



Rhimchthys atratulus me leagrt s (Agassiz) 



General description. — Active, streamlined minnow, 

 usually under 3 inches in length; color dusky or black 

 above with pronounced freckles or dark spots over top 

 and sides of body; black streak on side of body, 

 extending forward through eye and snout; scales small 

 but easily seen; small barbel clearly visible at each 

 corner of mouth especially when mouth is opened; fins 

 short and rounded; dorsal set behind pelvics; most 

 abundant in small, cool streams; rarely taken from 

 lakes or ponds. 



This form is found in clear, rocky streams from 

 New Brunswick to North Dakota and south to Iowa and 

 Alabama. 



The black-nosed dace spawns in April and May when 

 the water temperature of the creek reaches about 75 F. 

 The spawning site is located at the head of riffles. 

 They frequently occupy the same riffles used by creek 

 chubs — when the chubs are absent. Langlois C1941) 

 comments on the spawning activities: 



Each male occupies a "holding" though shifting around con- 

 siderably. When a female enters a "holding" the male goes to 

 her and sometimes passes several times around her before coming 

 to a lateral parallel position for spawning. When side by side, 

 the female vibrates her tail, sometimes nearly burying it while 

 doing so, and at the same time the male's tail starts v ibrating 

 and curling up over the female's tail to her dorsal fin, when 

 vibrations cease. Occasionally the pair remains in place and 

 spawns again immediately, but usually they separate, the male 

 darting forward while the female relaxes limply onto one side, 

 remaining there sometimes for several seconds. 



The milt and eggs may be stripped from ripe males and 

 females, and artificial fertili zation is practical. The eggs are 

 about 1/16-inch in diameter when laid but quickly swell to about 

 1/8 of an inch. 



