TROPICAL AQUARIUM FISHES 71 
THE ROSY-SIDED DACE 
Leuciscus vandoisulus 
One of the less known, but very attractive aquarium fishes is the 
Rosy-Sided Dace. The general color is silvery to green. A nearly black 
lateral line runs the length of the body, and below this on the males is 
a long patch of red, starting from the edge of the gills, as shown in 
illustration. This varies in intensity from day to day, and is brightest 
from February until September. As these fishes dart about the aquarium 
Fic. 52. Rosy-Sipep Dace (Life size) 
the flame-like appearance of the red patches is most striking. Even when 
not in color there is an interesting bronze-green effect to the scales at 
the lateral line. This is always visible by reflected light, and seems to 
show mostly at night. If the light is turned on them at night they show 
very little red color, but in a few minutes it is quite plain. 
The Rosy-Sided Dace is a large minnow and takes kindly to the 
aquarium and is perfectly harmless, but unless plenty of room is pro- 
vided it will slowly decline. Found in clear cool brooks, from the foot- 
hills of the Alleghenies to the Carolinas. 
THE BLACK-NOSED DACE 
Rhinicthys atronasus 
The Black-Nosed Dace is one of the best of our native fishes for 
aquarium purposes. Found in abundance in small swift-running streams 
of the Delaware Valley, it is an extremely active swimmer and not easily 
caught unless cornered in a small pocket. From constant swimming 
against the current it has developed some specialized kind of balance, 
so that when introduced into the still water of the aquarium, the forward 
part of the body continually drops so a level position is only main- 
tained by an effort. This condition disappears in a few weeks and a new 
equilibrium becomes established. 
