
AILMENTS AND DISEASES 

in breathing and the sloughing away of the skin. ‘The following are the 
recognized most common freshwater species likely to be encountered by 
the aquariist. 
IcHTHYOPHTHIRIUS MULTIFILIIS. This infusorian, Figs. 105 and 106, 
first forms round milky spots on the skin, fins, eyes and gills of freshwater 
fishes. A microscope examination will reveal that each spot is caused by 

FIG. 105. Ichthyophthirius multifilirs, an 
Infusorian parasite. Greatly enlarged. 
1. Ciliated spore. 
2. Segmentation upon encystment. 
3. Adult infusorian. 

FIG. 106. Head of a Catfish affected with Ichthyophthirius 
multiplits. 
the presence of a ciliated infusorian, the epidermis of the fish forming a 
considerable protuberance over the parasite. Sometimes two or three 
infusoria inhabit the same cyst, the form of the younger differing from 
that of the grown individuals. The fishes soon appear completely ema- 
ciated, the skin becomes thickened where the parasite 1s encysted, a scum 
forms on the surface and deaths occur in ten days to two weeks. 
PANTOTRICHUM LAGENULA (U. /agenula.) This infusorian, Fig. 107, 
is parasitic on the skin and in the gills of freshwater fishes and produces 
the “Spot-disease” or “Pox,” by living in the 
pulp cavity of the scales and absorbing their con- 
tents, pigment cells, etc., producing colorless 
patches on the skin. These spots first appear 

FIG. 107. Pantotrichum lagenula, as slimy excrescences, later assume a funguslike 
ee ee een appearance, and finally cause the death of the fish 
a pce ae a by emaciation and destruction of the tissues. 
The infusorian has an oval body with a sucking disc and swimming appen- 
dage, and the cuticle is covered with very fine evenly-developed cilia. 
TracHELocercip#. Of these infusoria the most frequently occur- 
ring freshwater species, is the ciliate Holotricha, HW. mystacca, Fig. 108,a more 
or less elongated or flask-shaped infusorian, entirely covered with cilia; 
with delicate flexible cuticle and the anterior part of the body at times 
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