LIVING FISHFOODS 139 



Blood Worms. In freshwater pools nearly everywhere can be found 

 deep-red, jointed worms about half an inch long. See Figure 127. 

 They usually stay at the bottom, living chiefly on decomposing vegetal 

 matter. Often they will writhe their way awkwardly through the water in 

 a series of figure eights. They are the larvae of midges and form an 

 important article of diet for our native fishes. They are often found in 



Fig. 127. Bloodworm (Enlarged four times) 



large numbers in daphnia pools and should always be taken when possible. 

 If too large for the young fish, they make choice morsels for the older 

 ones. 



Tubifex Worms. These are small thread-like worms living in mud 

 and sand. They form a tube or case below the surface, extending the 

 upper ends of their bodies from this in search of small organic food, 



Fig. 128. Tubifex Worms (Magnified, and as they appear to the naked eye) 



causing a circulation of water about themselves by a constant weaving 

 motion. When alarmed they draw back into the case. They are exten- 

 sively cultivated in Europe as a food for tropical fishes. A similar variety 

 is often introduced into goldfish aquaria when feeding daphnia, where 

 they become an unsightly nuisance, for goldfishes cannot catch them. To 

 get rid of them it is necessary to boil or renew the sand or else keep other 

 fishes in the aquarium for a long time. The worms have to be eaten off 

 many times before the stock dies. Germicides strong enough to kill them 

 will also destroy the plants, as they can withdraw into the sand. Along 

 the edges of ditches they are often so numerous as to make a solid rusty- 

 red color. If they are scraped up together with the mud and then washed 

 free they are greatly enjoyed by gold and tropical fishes, but it is inadvis- 

 able to introduce them where there is sand or soil. 



Fig. 129. Freshwater Shrimp (Enlarged three times) 



Fairy Shrimp (Gammarus). While freshwater shrimp is not plenti- 

 ful enough anywhere to feed in large quantities, it is a delicate morsel for 



