172 ] Fish and Their Fabulous Neighbors 



until they reach the North Sea. There are still other migrations 

 that take fish from the salty ocean to fresh inland waters to de- 

 posit their eggs. 



How to Keep an Aquarium Successfully 



A home aquarium may be a simple matter of keeping one or 

 two goldfish or it may be a full-scale hobby involving a variety 

 of fishes. Tropical and toy fishes are more difficult to raise than 

 the goldfish, but even this hardy pet requires certain favorable 

 conditions in order to survive. 



The goldfish needs adequate amounts of water about a gallon 

 for every inch of fish in the tank. It must be given food in proper 

 amounts; overfeeding is a far more common trouble than insuffi- 

 cient food. The water must be kept clean yet the fish must not 

 be subjected to a sudden change in temperature when fresh water 

 is provided. The tank must have the right amount of sunlight, 

 not too much, not too little. Several hours of hot summer sun 

 may kill the occupants of a small tank. 



Plants are attractive in an aquarium and give the fish a sheltered 

 place to rest and possibly to lay eggs. Contrary to general opin- 

 ion, they are not essential, however, and too many plants are 

 harmful rather than beneficial. 



The popularity of goldfish has put goldfish breeding on a 

 substantial commercial basis. A goldfish hatchery near Frederick, 

 Maryland, covers 150 acres and turns out about five million fish 

 a year! 



How LONG FISH LIVE 



Properly cared for, the common goldfish may reach an 

 age of twenty-five or thirty years. Many species of fish have a long 

 life span, but in the natural state they are not likely to live to a 

 ripe old age: They have too many enemies, and some such as 

 the Pacific coast salmon die after spawning. However, records 

 of fish in ponds or aquariums tell us of catfish that lived sixty 

 years, halibut that rounded out thirty, and trout that flourished 

 for eighteen years. 



