132 FEESH-WATEE AQrAEIA. 



of flies, midges, and other insects, and various decaying matter ; 

 but in the aquarium they should be fed upon vermicelli, 

 to which flies may be added when they can conveniently 

 be obtained. Though while at liberty in the river the 

 Bleak is said to help to purify the water by feeding upon 

 decaying substances, the aquarium-keeper must not think 

 that he is- providing food for his fish by allowing such 

 matter to remain in the tank. It is never wise to presume 

 upon the presence of any scavengers in the aquarium ; but 

 to constantly attend to the cleanliness of the tank, as if 

 there were no such animals. The scavengers will find 

 plenty of food, notwithstanding all the owner's care. Bleak 

 can be caught by fishing for them with a fine line and a 



Fig. 99. Stone Loach (Coeitis barbatula). 



very small hook, baited with a fly or gentle : the hook 

 should be quite hidden by the bait. The Bleak is the 

 narrowest and flattest British fresh-water fish, its body 

 being shaped very like that of a sprat. The colour of the 

 back is a faint brownish-green, and the rest of the body 

 is a glittering silvery-white. The dorsal fin is small and the 

 anal fin large. The lower jaw projects beyond the upper. 

 The Bleak is about 7in. long when full grown. 



Many people who keep aquaria declare that the Stone Loach 

 (Cobitis barbatula) (Fig. 99) is a delicate fish, and will not 

 live for any length of time in confinement; and they are 

 right, for it will not continue very long in health in an 

 ordinary deep tank. In such an aquarium it will be often 

 seen, especially towards evening, rising in its curious newt- 

 like motion to the surface of the water, and after obtaining 



