AILMENTS AND DISEASES 



by the head, to close the operculae and mouth, and the rest of the body 

 immersed for five seconds, the treatment to be repeated at intervals of one 

 day. All newly acquired fishes should be so treated before introduction 

 into an established aquarium. No ill results follow and salutary effects 

 are certain. 



A recent highly recommended remedy is the Antigyrodactylin,* 

 of Paul Nitsche, for the extirpation of surface parasites on fishes, especially 

 those of the aquarium. The fishes should be well fed about two hours 

 before treatment and receive no food three hours thereafter. The treat- 

 ment is to be applied three succeeding days. The fish is to be taken by 

 the head and gently passed backward and forward through the Antigyro- 

 dactylin for i ^ to 1 3^ minutes, not longer. Then it should be 

 placed in a vessel containing well-aerated water, that the parasites may 

 drop off and sink to the bottom. After five minutes it should be 

 transferred to a second similar vessel, and then, after expiration of another 

 five minutes, to a third large shallow-water vessel containing just sufficient 

 water to enable the fish to swim. This water should be changed daily and 

 the vessel scoured. It is advisable to have the water of each vessel one or 

 two degrees colder than the prececiing, on account of its effect on the 

 parasites, as it will aid in their leaving the fish. 



If the fishes show indications of exhaustion after the bath, they should 

 be kept in motion for some time with a light wooden rod. 



A litre of Antigyrodactylin is sufficient for the treatment of twenty 

 fishes. Taken internally it is poisonous, but is harmless externally, even 

 on wounds and abrasions. 



Vegetal Parasites and Parasitic Diseases. All animal and vege- 

 table substances are subject to the attack of low forms of vegetal parasites, 

 and though they are not all necessarily malignant, many of the diseases of 

 aquatic animals and plants are directly due .to the presence of these micro- 

 organisms, which are saprophytic upon the dead and parasitic upon the 

 living tissue. 



The vegetal parasites found on animal bodies belong to the class of 

 Cryptogamia and the orders Algae and Fungi; distinguished from each other 

 by the presence of chlorophyll or other coloring substances in the former 

 and their absence in the latter. 



Parasitic Alg^e. The aquatic forms of this order, or those which 

 have preserved some essential algal features, found on animals, consist of 

 single or branching, cylindrical or flattened filaments,which have no method 

 of fixing themselves but are firmly held by the crossing of their fibres. The 

 reproductive system consists of round or oval spores enclosed in a case or 



*To be obtained of H. Lehmann & Co., Chemists, Berlin. 



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