55 



this disease is accomplished by dipping in a 1:2,000 

 solution of copper sulphate (6.5 ounces to 100 gallons 

 of water) for 1 or 2 minuter. Specimens on which the 

 disease has progressed to a marked degree should be 

 destroyed, as the dip can do little for them. Bacterial 

 fin rot has also been controlled with a 1:4,000 (8 

 ounces to 100 gallons of water) solution of formalin 

 used as a dip for 1 hour. 



Black grub, — Black grub or black spot is caused by 

 the larval form of the flatworm, ffeascus sp. The para- 

 site occurs on fishes as a small black spot about 1/25 of 

 an inch in diameter. This black cyst encloses a small 

 worm which is usually limited to the scales and integu- 

 ment but which may occasionally be found in the flesh 

 just below the skin. The life history of the black 

 grub is complicated but is typical of many of the 

 flatworm parasites. The adult worm occurs in the 

 kingfisher. Eggs of the worm are discharged into the 

 water, where they hatch into small free-swimming organ- 

 isms. These larval forms swim about until they come 

 in contact with a particular species of snail. Then 

 they bore into the snail and reproduce themselves many 

 times. Finally, numbers of free-swimming forms break 

 out in the water and move about until contact with a 

 fish is made. They then burrow in and encyst in the 

 scales or in the flesh. When the fish is eaten by a 

 kingfisher, the encysted worm develops into an adult 

 and the life cycle is completed. It usually causes 

 little damage to the fish but may, at times, be present 

 in numbers large enough to cause death. 



Klak (1940) reports a heavy Neascus infestation 

 of fat-headed minnows in a pond at Leetown ( W. Va.). 

 The encysted worms were found in the abdominal cavity 

 in such numbers that the abdomen was greatly distended. 

 Mortality was so high that a change to golden shiners, 

 a more resistant species, was recommended. 



The only controls for this parasite are draining 

 the pond long enough tckill the snails, and controlling 

 the kingfisher population. 



Ligula intestinalis. — This is a tapeworm whose last 

 larval stage is commonly found in the body cavity of 

 suckers and minnows and rarely in perch, darters, and 

 bass. Infested fish are easily recognized by their 

 swollen bellies; worms 6 inches long have been taken 

 from minnows, and worms as long as 12 inches have been 



