THE PUBLIC AQUAEIUM 303 



The New York Aquarium has kept specimens of <rar (Lepisosteu^s) , 

 mudfish {A?nia), and striped bass {Roccus) for 24 years. INIany 

 of these are still living. Among fishes that have lived 12 years or 

 longer are three species of sunfish {Lepomis)^ rock bass {Amhlo- 

 pUfes), calico bass {Ponwxis) , and perch {Perca). There is a 200- 

 pound jewfish {Promicrops) that has been living in one of the tanks 

 for nine years. There is a similar record for the nurse shark 

 {Ginglymo^toma) , although it has not yet reached a length of 3 feet. 

 Many species of groupers [Myctero perca), hinds {EpinepheJus), and 

 grunts {H((^mulo)i) are living in the tanks after more than eight 

 years of captivity. The list of long-lived fishes could be extended 

 greatly. A sea lion {Zalopkus) lived 19 years in one of the large 

 pools, and a giant salamander {Cy^yptohranchus) is still living after 

 13 years. On the whole, the records for aquarium exhibits are 

 probably as good as those of the average zoological garden. They 

 can undoubtedly be made much better with improved methods of 

 feeding. 



CLEANING TANKS 



All tanks containing living exhibits require cleaning at times. 

 This procedure causes disturbance that is more or less harmful to 

 the occupants. No fixed rule on cleaning can be laid down, owing 

 to the varied conditions that prevail in a series of tanks. Some of 

 the larger hshes are affected but little, while many of the smaller 

 kinds become alarmed. 



Tanks of small or medium size usually are cleaned by siphoning 

 with a 1-inch hose, with only partial lowering of the water. At 

 times it is desirable to use a long-handled brush in cleaning the 

 inner surface of the glass. The rockwork lining of the tank requires 

 occasional brushing, which can also be done without lowering the 

 water. Crevices in the rockwork can be reached only b}^ using a hose 

 with a strong flow after the tank has been drawn as low as safet}^ 

 permits. 



The large tanks are half emptied for cleaning by opening the 

 bottom drains. While the water is flowing out wastes and sediments 

 are swept carefully toward the drain. Frequent use of the hose 

 siphon serves to reduce the necessity of frequent cleaning with the 

 brush. 



Frightened fishes are liable to injure themselves if tank cleaning 

 is left to careless persons. In cleaning fresh-water tanks the waste 

 water goes to the sewer line; in tanks containing stored sea water, 

 to the filter. Fresh-water tanks need frequent cleaning at times 

 when Saprolegnia is troublesome. This fungus forms quickly on 

 bits of unconsumed food that have not been removed. 



The keeping of numerous crabs, crayfishes, or lobsters with such 

 fishes as are not inclined to disturb them is desirable. They are not 

 only of value as exhibits but assist in the removal of unconsumed 

 food. Floor pools, being occupied by heavy feeders, should be 

 emptied daily and cleaned with long-handled brushes if they are 

 to be kept in sanitary condition. 



