METHODS OF COMBATING FUNGUS DISEASE ON FISHES IN 



CAPTIVITY. 



By CHARLES F. HOLDER. 



The few suggestions made in this connection are the result of observations 

 made in several tank aquariums and a series of open-reef aquariums on the 

 Florida coast for the study of corals and fishes. 



Fishes in confinement are subject to fungus disease in a ratio as the conditions 

 under which they are kept differ from those of their normal habitat. Such 

 differences vary largely with the intelligence or ignorance of the keepers, or their 

 carelessness. Fishes are handled improperly, have been injured previously or 

 in their capture; they are overfed and food collects in the tanks; aeration is 

 incomplete ; there is an overabundance of algae ; or the cement of the tank may 

 be poisonous. All these factors are causes of disease, as I observed in the 

 New York Aquarium in 1873, in the Santa Catalina Zoological Station in 

 1 903- 1 908, and in Florida where aquariums were built out into the reef. 



It has been my experience, then, that if preventive measures are sufficient 

 few fish are diseased or lost, and the point of my suggestions relating to fungus 

 affecting a species of fish under cultivation is that the Chinese method of materia 

 medica should be adopted — namely, not to cure but to keep well. A set of 

 rules bearing on the prevention of disease should be observed by every aquarium 

 attendant. Such rules are as follows: 



I. Never take out fish with the bare hands. Lift them carefully with a 

 large fine-mesh net. Under no circumstances touch them, as handling often 

 produces fungus. 



II. Give the fish proper and natural aeration. The surf or near-shore fishes 

 require more or direct aeration ; deep water forms require less. 



III. Never allow food to collect in the tank. Have every tank supplied with 

 an abundance -of natural scavengers — crabs of various kinds, barnacles (sea 

 water). In fact, it should be the most important qualification of an attendant 

 to know how to equip a tank to give the fish natural surroundings. The habits 

 of the fish should be known, its usual food given it, and the balance should be 

 preserved in the tanks, each being supplied, so far as possible, with the conditions 

 found in natural life. 



The following are some experiments successfully tried at the Avalon 



Zoological Station. 



935 



