108 



Aquatic JLite 



ergy for sale at eleven cents a kilowatt 

 hour this device, using one-tenth of an 

 ampere, will produce half a liter of oxy- 

 gen gas in one day for three cents, using 

 four-fifths of a cubic centimeter of water 

 in so doing. 



The apparatus must be used on direct 

 current, and the anode must be connected 

 to the positive pole. The proper pole 

 may be ascertained as follows : Take an 

 old carbon electric light bulb and knock 

 the tip off under water, allowing it to fill 

 up. Put in a drop or two of phenol- 

 phthalein. Connect to socket. A pink 

 stream will be seen issuing from the 

 broken end of the negative wire inside the 

 bulb. 



The glass tube should be placed ver- 

 tically in the aquarium, so that the glass 

 cup just clears the bottom. It may be 

 conveniently supported by an iron-ring 

 stand and clamp. 



On one occasion I kept thirty-two 

 fishes, averaging two inches in length — 

 goldfish, dace and shiners — in a three- 

 gallon tank for three weeks without 

 changing the water. At the end of this 

 time a chemical analysis of the water was 

 made for oxygen. The result, 8.95 parts 

 per million (by weight) of dissolved oxy- 

 gen, showed the water to be in a state of 

 3 per cent, super-saturation. 



Beef vs. Liver 



An interesting experiment has just 

 been undertaken at the Wytheville (Va.) 

 station in the feeding of beef liver and 

 beef heart to young rainbow trout. In 

 each of two 14-foot troughs 10,000 fish 

 just ready to take food were placed. The 

 water temperature for the first 30-day 

 period was approximately 55 degrees F., 

 and a flow of about seven gallons per 

 minute was maintained. All the fish in- 

 cluded in the experiment were selected 

 from the same lot, and their treatment in 



the troughs was identical in every way, 

 with the exception that those in one 

 trough were fed on heart and those in 

 the other trough on liver. The results 

 were as follows : 



Fed on beef heart : 



Weight at beginning 5 oz. per 1000 fish 



Weight after 30 days. . ..10^4 oz. per 1000 fish 

 Fish lost during period 156 



Fed on beef liver : 



Weight at beginning 5 oz. per 1000 fish 



Weight after 30 days 10 oz. per 1000 fish 



Fish lost during period 275 



From this it will be seen that the rain- 

 bow trout fed on beef heart suffer less 

 mortality and also gain slightly in weight 

 as compared with those fed on beef liver. 

 With the continuance of the experiment 

 the results may be more striking. Much 

 discussion has been carried on at the 

 various stations as to the relative merits 

 of heart and liver as food for fish, and it 

 is thought this experiment if extended 

 and confirmed, may be of practical value. 

 — Fisheries Service Bulletin. 



During April 



How foolish 'tis to sit and sigh, how 

 needless is the pain ; thinking every cloud 

 in the sky means bucketsful of rain. 



To derive the maximum enjoyment 

 from aquarian nature-study one should 

 possess and learn how to use a micro- 

 scope. Avoid instruments for which ex- 

 travagant powers are claimed, especially 

 when the price is ridiculously low. Such 

 usually lack the name of the maker,. The 

 maker of a good stand has reason to be 

 proud of his work, and therefore places 

 his name upon it. The cost of a micro- 

 scope sufficient for the needs of the 

 aquarist, made by a reputable firm, need 

 not be great. 



For "pep and punch" does any other 

 fish beat the Chanchito? 



