AILMENTS AND DISEASES 



Batrachosperms are small gelatinous masses of Algae which attach them- 

 selves to plants and submerged wood. 



Lemanea grow in masses and form a turf-like covering on stones in 

 water often two inches long. Some of the forms of this genus are present 

 in all freshwater. 



Nostocs c^ruleum, N. depressum, N. sp^ricum and N. lobatus, are Algs 

 which adhere to aquatic plants and form tiny dark-green, brown and 

 blackish tufts. 



Cylindrospermum minutus, forms filamentous light-green to rusty-brown 

 intricately felted minute masses on aquatic plants. 



Gloiotrichia incrustata, forms tiny clusters of light-green, straight and 

 stiff filaments bearing round fronds the size of a mustard seed on water 

 plants. 



Rivularia cartilagina, appear as sub-globose, stiff, deep brown or 

 blackish threadlike filaments, having small semi-globose fronds or cells 

 containing spores, and attach themselves to aquatic plants. 



Scytonema immersus, and S. nagelii, 'form dark green mats on aquatic 

 plants, and S. dubium, dark masses binding the leaves together. 



Other Algae which cause green water and scum on ponds and stagnant 

 water are Oscillaria, Hydrodictyon, Zygnomacia, Wolffia and Vaucheria. 



Diatoms and Dismids are also often present in great numbers. These 

 serve as food for fishes, and are in part the first food of the alevin and fry, 

 their silicious casings aiding in the development of the bones. 



Conferva. The Cladophora are the larger members of this genus, 

 two of which are common in Eastern waters. These are CI. fracta and 

 CI. brachystelecha. They seldom occur in 2iQ^2Lr\-ii,\)\!iX. Scenodesmus polymor- 

 phus, develops in quiet pools and ditches in such numbers as to make 

 the water clouded and very green. It consists of short and slender fila- 

 ments with tiny threadlike branches. 



Aquarium fanciers have been led into considering all minute water 

 plants as Confervae. They are a small group of the large family of Algae, 

 and mostly of larger size than those which occur in aquaria. 



Slime Fungi. When the sides of breeding tanks do not become 

 coated with algas, two or three species of the Myxogastres or Slime Fungi 

 are likely to form. These are injurious to the spawn and young fishes 

 and should be removed. 



Plant Fungi. A number of injurious fungi on the larger aquatic 

 and semi-aquatic plants are likely to be encountered by the aquariist. The 

 more general of these are: — 



Rhizopus necans, affecting lilies introduced from Japan. It lives as 

 a saprophyte in the soil and becomes a wound parasite, gaining access 



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