LAMPREYS AND FISHES 



A pair of the hardier sticklebacks (p. 339) will sometimes 

 nest and carry on all their egglaying activities in a comfort- 

 able aquarium supplied with their building materials. 



Fall is the best time to collect fishes for aquaria. They 

 are in good condition then and during the cool weather it is 

 easier for them to get used to the close aquarium. When 

 they are newly captured they are liable to jump out of the 

 water; they are safer if the aquarium is kept covered with a 

 screen. If an aquarium is properly balanced the water will 

 not need changing (p. 39) ; and if cleaning becomes necessary, 

 it is better to pour the old water out, strain it, aerate it by 

 pouring it through the air, and then use it again. Fishes get 

 on best in the old water to which they have grown accustomed. 



There are several good books on aquarium making; soma 

 of these are listed in the Bibliography (p. 409). 



Common brook and pond fishes. — A few families of ponJ 

 and small-stream fishes are briefly discussed here. These are 

 selected because they are common, or easy to observe, or both. 

 Keys and more particular descriptions can be found in. Jor- 

 dan's "Manual of the Vertebrates" and other books named 

 in the Bibliography (p. 421). 



Fig. 270. — Lake lamprey, Petromyzon mariniis, 

 attached to a fish. Above the pectoral and ventral 

 fins are scars showing where other lampreys made 

 ragged openings with their rasping tongues. (Pen 

 drawing by S. H. Gage.) 



Lampreys. — PetromyzonidcB 



Lake lamprey, Petromyzon marinus. — ^Lampreys are neither 

 eels nor true fishes although they resemble both. Almost 



327 



