78 FISHFOOD 



conditions cypris multiplies with astounding rapidity. It has been claimed 

 that they devour spawn and young fishes. This is undoubtedly an error, 

 but they do greatly annoy snails and eventually cause their death by 

 getting into some inner recesses of the animal. 



Blood Worms. In freshwater pools nearly everywhere can be found 

 deep-red, jointed worms about half an inch long. They usually stay at 



Fig. 60. Bloodworm (Enlarged four times) 



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 large numbers 

 in daphne pools and should always be taken when possible. If too 

 large for the young fishes, 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, 

 causing a circulation of water about themselves by a constant weaving 



Fig. 61. Tubifex Worms (Magnified, and as they appear to the naked eye) 



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. 



Infusoria and Rotifera. Of prime importance as food for very small 

 fishes are the Infusoria and other microscopic creatures in water. Some 

 idea of their minuteness may be had when it is pointed out that they 



