246 ANIMALS AT WORK AND PLA Y 



the weed, and raise their tails, which wave about in 

 the weeds, or even above the surface of the water. 

 They are eating the weed bare of the clinging film 

 of microscopic larvae, of water-fleas, Cyclops, and other 

 fresh water entomostraca. The trout is the most easily 

 fed of all fish, being greedy, omnivorous, and not 

 afraid of artificial food, such as bread or paste. But 

 the kind of food with which it is supplied makes a 

 vast difference in its growth. Experiments made on 

 trout showed that when fed upon worms only they 

 grew slowly ; others fed on minnows did better, but 

 a single fish fed upon insects weighed twice as much 

 at the end of the experiment as a pair of those reared 

 upon worms and minnows respectively. For feeding 

 all young trout the microscopic food is now admitted 

 to be best of all. Mr Armistead, in a recent lecture 

 on * Fish Culture ' at the rooms of the Royal Institu- 

 tion, dwelt on the necessity for making separate pools, 

 full of weeds and plants, in which the millions of 

 entomostraca might increase, and serve as food for 

 the young trout below. Carp were formerly believed 

 to be vegetable feeders, and the carp ponds of Ger- 

 many used to be drained and planted with rye as 

 carp food. So it was, but only as being itself food 

 for the microscopic millions. The carp chews the 

 water-weed, sucks off the insects, and then spits it 

 out again. It may be doubted whether there are 



