THE CARE OF HOME AQUARIA 31 



It is difficult to lay down any hard and fast rule for this, 

 because the number of fishes that can be kept depends upon their 

 size and kind as well as upon the proportions of the tank and the 

 amount of plant life in good thrifty condition. It may be stated 

 that the beginner will do well to supply only a couple of fishes 

 three or four inches long to an aquarium of five or six gallons of 

 water when the plants are in good condition. A rule often given 

 is— one inch of fish (not counting the tail) to each gallon of 

 water. That is to say, a six-gallon aquarium will ordinarly sup- 

 port six fishes an inch in length, or two fishes three inches long. 

 When he is well acquainted with the habits and appearance of 

 his fishes, the aquarist will be able to know at once when his 

 tanks are overstocked before any losses take place. 



Strange fishes should not be introduced into an aquarium 

 with others until they have proved free from disease. They 

 should be kept by themselves for a week at least, and for the 

 purpose of sterilization, may be placed in a bath of permanga- 

 nate of potash. This substance in stronger solutions is highly 

 poisonous to fishes. The bath in proper concentration, has a 

 light claret color and the fishes should be watched closely while 

 in it. If they show any signs of turning on the side, they should 

 be removed at once to pure water. Snails and other animals may 

 be treated in the same manner for the purpose of disinfection. 



There are, of course, many sorts of animals besides fishes 

 that are adapted to aquarium life. The tadpoles, larvae of frogs 

 and toads, are easily collected in any pond, or some of them may 

 be purchased from dealers. In addition to their interesting 

 habits they are useful as scavengers, but unless they are large it 

 will not do to introduce them into the aquarium with carnivor- 

 ous fishes. In early spring the eggs may be collected and the 

 young reared. The eggs of the frogs are laid in gelatinous 

 masses, those of the toad in long strings. 



Of the numerous salamanders, the pale axolotl and the com- 

 mon mud-puppy (Nectiirus) both of which have external gills, 

 are easily kept. The eggs of the mud-puppy can often be ob- 

 tained in large masses in ponds in early spring, and the larvae 

 may be reared as easily as those of the frog. The most attractive 

 of the native salamanders is the common or spotted water newt 

 (Diemictylus viridescens) . These beautiful and graceful little 

 animals, though without gills, live well in the aquarium, since 

 they are apparently able to absorb sufficient oxygen through the 

 skin. They swim readily with the limbs folded against the sides, 



