12 AQUARIUM MANAGEMENT 



Temperature. The larger the water surface, the higher tempera- 

 ture the fishes can stand. A practical general standard for goldfishes 

 would be from 65 to 75 degrees in summer and from 50 to 65 degrees 

 in winter. Newly-hatched goldfish fry imder six weeks of age do 

 well in temperatures between 75 and 85 degrees. Floating ther- 

 mometers with red or blue spirits are easily read and are of value m 

 aquarium work. 



Green Water is caused by the presence of microscopic forms of 

 vegetable life suspended or swimming in the water. Their growth is 

 usually promoted by a combination of too much direct sunlight and a 

 large number of fishes in the aquarium. There are several ways of 

 clearing the water. First change it, add a few fresh-water mussels, 

 cut down the light by use of tissue ]iaper, ground glass, frosted var- 

 nish on the glass, or other means, and reduce the number of fishes. 

 To clear the water chemically, add one grain by weight of perman- 

 ganate of potash (dissolved) to each gallon of aquarium water. This 

 will turn the water first a lavender, and then a brownish color for a 

 few days, after which it will clear up. Unless the original conditions 

 are changed, however, the water will soon again become green. 

 Before using this chemical remove all snails and mussels. Goldfish 

 can withstand the strength of the sf)lution recommended, and prob- 

 ably be benefited if suffering from any form of fungus. (See Chap- 

 ter on Diseases.) Other fishes do not stand this chemical so well. 

 Green water, while unsightly, is not unwholesome. On the contrary, 

 a sick fish is often cured by being transferred to a tank of green 

 water. Live daphnia (page 134) will clear water in a few days. 



How to Know When the Fishes are Sick. The first signal of 

 distress in most fishes is the drooping of the dorsal (back) fin. This 

 fin should be carried stiff and upright. When the fish is sick its 

 movements are sluggish and it often seeks a quiet corner in which to 

 hide. In some of the fancy varieties the dorsal fin is so over-devel- 

 oped that the fish even in health has not sufficient strength to hold it 

 erect. When such fishes are ill their fins become more or less stiff, 

 losing flexibility. Fins shovUd be clear and clean-cut. When they 

 become thick-looking, opaque, lined with red veins, overcast with red, 

 bloodshot at base, or ragged and split, the fish is in need of attention. 

 (See Chapter on Diseases.) Another sign of poor condition is thin- 

 ness of the body. The excrement of fishes in health is usually of a 

 dark color. When it is pale, dotted with gas bubbles, and of slimy 

 appearance, the fish is apt to be out of condition. 



