1 70 ] Fish and Their Fabulous Neighbors 



Fish Scales 



The scales of a fish look a good deal like the shingles on a 

 roof. Each of the scales grows separately from the skin, but they 

 are set at an angle so that they overlap and form a complete cov- 

 ering for the body. Naturalists sometimes call this scaly covering 

 the "outside skeleton." 



Some fish, the catfish for one, do not have scales. Among the 

 species that do have scales, a newly hatched fish of the bony group 

 lacks the protection of scales for its skin; but it does not take long 

 for them to develop. Some kinds of scales those of the eel, for 

 example are so tiny that you can hardly notice them. A curious 

 feature of some members of the tuna family is that they are only 

 partly scale-covered. 



TELLING THE AGE OF FISH 



As the fish grows, its scales grow too. You can tell the age 

 of many of the bony fish by the markings on their scales; by exam- 

 ining the rings you can tell how many birthdays they have passed. 

 Of course you will not want to do this with your goldfish pet: 

 Its scales should never be touched, let alone pulled out of the 

 skin. A protective slime covers the scales and if this is rubbed off 

 by dry hands or in any other way, death may result for the fish. 

 Children enjoy studying the scales cleaned from a fish destined 

 for the family dinner. Any youngster who knows how to count 

 will get a thrill looking at the scales through a magnifying glass, 

 checking the number and nature of the rings, and reporting the 

 age of the main course for dinner! 



"It Was That Big!" 



Among fish, size is not so standardized as among mammals. 

 The goldfish is an outstanding case in point. In an aquarium it 

 remains small, whereas, given the freedom of a pond, it increases 

 its size many times over. Such factors as the temperature and 

 acidity of the water and the type of food available limit the 

 length and weight a fish can attain. 



Most of the really big fish are found in the ocean though there 

 is a huge species, the arapaima, that lives in the rivers of Brazil 



