EXPERIMENTAL FISH EMBRYOLOGY 565 



c. Add the Pablum (or Seravim) to form a thick paste. Mix well. 



d. Place the mixture In small glass Jars, and cover hut do not screw the cover 



on. Set the Jar (containing liver-Pablum mash) in water, and hring the 

 water to a hoil. Turn the fire off and let the Jar stand In the boiling 

 water about one-half hour. This serves to coagulate the blood and other 

 liver proteins without destroying the valuable vitamins. It also pasteu- 

 rizes it to some extent. Screw top on tightly. Keep in cool place 

 (refrigerator) where it will last a month, if not opened. 



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The fishes are fed once each day, generally early in the morning, so 

 that they have the entire day to clean up all the food that is given to 

 them. The uneaten food should be removed at the end of the day, if pos- 

 sible. No fxirther feeding should be made when there is food left in the 

 tank. The food may be added to the tank from the end of a scalpel, the 

 amount being about the size of one rice grain per fish (unless they are 

 very large fish) . The fish will soon learn to come for the food, tear it 

 apart, and eat it all. 



FISH DISEASES : 



It is almost safe to say that there is no reliable remedy for a sick fish, no matter 

 what the cause. Prevention is all important for really there Is no cure.' However, there 

 are several simple rules to keep in mind: 



1. Never add new fish to an old aquarium until they have been sterilized and have 



been quarantined for a few days. All new fish should be given a salt treatment, 

 regardless of their source. 



2. Provide separate aquaria for sick fish and isolate them as soon as there la any 



indication of trouble. 

 5. When shipping large numbers of fish it is said that mortality will be reduced if 



a small amount of aspirin is added to the water (reasons unknown). 

 k. When sick fish are found in a regular aquarium, thla aquarium should be put through 



a thorough process of cleaning and sterilization. Fish diseases are generally 



very contagious (for the fishi ) • 



5. Overcrowding and overfeeding are probably the second and third most frequent causes 



of illness, the first being parasitization. 



6. The chlorine in drinking (tap) water is a good bactericidal for human beings but 



harmful to the fish. Chlorine will naturally evaporate from standing water if 

 there is sufficient exposed surface, but warming or agitating the water will 

 hasten the process. 



Some fanciers recommend a tonic salt bath for all fish once each month. Such a bath 

 is made by adding 5/I+ teaspoonful of NaCl and ^ teaspoonful of Ejjsom Salts (MggSOi^) to a 

 gallon of boiled and cooled tap water. The fish may be left in this for 2U hours. If 

 the fish are definitely sick, the dose should be increased by using only one quart of water 

 and expose them for ^ hour, or less if they Indicate Intolerance of the treatment. 



Nigrelli (19'<-3) tas made a thorough analysis of the diseases (and other causes of 

 death) of marine, temperate, and tropical fish. Some of the parasitic, and infectious 

 diseases and other causes of death he lists are: 



Parasitic and infectious diseases . 

 Diseases of the skin and gills: 



Saprolegnla ( fungus 1 



Tuberculosis 



Ichthyophthirius (a Ciliate) commonly called "Ich". 



Gyrodactylids (a Trematode) 

 Diseases of the circulatory organs: 



Ruptured sinus venosus (due to Gordild worms). 

 Diseases of (general) internal organs: 



Mechanical destruction (by Gordild worms). 



