AILMENTS AND DISEASES 



FIG. 1 08. Holotrichuzmyitacca^ 



an Infusorian parasite. Greatly 



enlarged. 



FIG. 109. ChrQmatot>haguB parasiticus^ an Infusorian 

 parasite. Greatly enlarged. 



extended like a porboscis. It is most frequently 

 observed on fishes kept under unsanitary conditions 

 or which have become exhausted from fright, trans- 

 shipment or other disturbing causes. 



The following are nearly related forms. 

 Chromatophagus parasiticus. On the 

 bodies of freshwater fishes, very distinct milky-white 

 spots develop, caused by these large infusoria lodg- 

 ing on, or in, the epidermis, which show a distinct rotating motion between 



the epidermic cells. Fig 109. These 

 parasites are usually single, but some- 

 times two or three are imbedded close 

 together. Their shape is variable but 

 most often oval with the longer diameter 

 0.615 mm. and the shorter 0.408 mm. 

 The body is enclosed in a thin elastic 

 cuticle covered with fine cilia, the layer 

 below finely granular, filled with a large number of contractile vacuoles of 

 different size. They have a proboscis-like sucking tube. The presence of 

 these parasites is manifested by the formation of cysts on the surface of 

 the fishes, which enlarge until the skin and head are covered by funguslike 

 postules in which the boring infusoria are encysted. Death results from 

 exhaustion and the ravages produced by the parasites. A similar infusorian 

 has been found in the blinded eye of a Telescope goldfish. 



Tetromitus nitschei. This infusorian. Fig. no, previously re- 

 cognized as Contia necarix, is supposed to have only the Japanese Fringetail 

 goldfish as host, but a very similar species, Bodo necator, is very destructive 

 to young trout in Europe, and the described form is 

 probably a Japanese species of the same genus. This 

 minute organism attaches itself to the surface and under 

 the scales in vast numbers, often hundreds in a space as 

 large as the head of a pin. Its presence is manifested by 

 excessive mucous coating, red spots and ulcers. In the 

 free-swimming stage it has a flattened appearance with 

 cilia at one side by means of which it moves through the 

 water until it comes in contact with its future host. 

 When not checked this parasite may become so numerous 

 as to cause the destruction of all the fishes in an aquarium. 

 None of the other mentioned orders of Infusoria 

 are parasitic on fishes but a considerable number occur with other lower 

 forms of aquatic fauna. 



FIG. no. Taromitus 



nitschei f ( Contia necarix) 



an Infusorian parasite. 



Greatly enlarged. 



