564 REPORT OF COMMISSIONER OF FISH AND FISHERIES [98] 



ill wheelbarrows, and in very large ponds one-horse carts may be used, 

 from which the mud can easily be dumped. In removing mud from 

 a pond, special care should be taken to do this evenly throughout the 

 entire pond, so as to .prevent the formation of holes in the bottom, whi(*h 

 would seriously in.terfere with the fisheries. It would, however, be a 

 mistake to remove every particle of mud from a pond, as this Avould 

 diminish its food-producing capacity, but it should always be allowed 

 to remain to the depth of 30 to 40 centimeters. If the mud is to be 

 taken from very large ponds, it will be impossible to accom])Iish this by 

 carting it away, as this would involve too much labor and expense ; and 

 it will become necessary, immediately after the fisheries, when the mud 

 is still in a fluid condition, to have it carried away with the water. To 

 do this, runiiiiig water should be led to the deepest places ; or special 

 ditches should be dug, to which the mud is carried fiom all sides, and 

 whence the Mater carries it farther, and finally out of the pond through 

 the pipes, which ])rocess should be aided by rakes, shovels, and brooms. 

 This process will of course, require rapidly running water, whose course 

 may be accelerated by occasionally driving in the tap and quickly pulling 

 it out again. This i)rocess should be continued until the pond has been 

 suiticiently cleaned of uuul. If possible, the bottom of a pond which has 

 undergone this process should be plowed, and not be allowed to dry 

 out, but should be immediately filled again with water. 



i^ickncss amoruj Jiah. — By cleaning the pond annually and by aiding 

 the influx of water, the health and growth of the fish will be greatly 

 promoted. If the water is very low, and if there is too great an accu- 

 mulation of mud in the pond, the temperature of the water will, in hot 

 summers, become too high, too nuich oxygen will be absorbed, the decay 

 of vegetable and aninuil matter will be very great, the water will 

 deteriorate, the fish will perish, unless either a timely supply of fresh 

 water is introducnl into the pond or the windows of the sky are o})ened 

 and hel]) comes from above. To this danger fish are particularly ex- 

 posed in sky i)onds in which it is difficult to keep up an even height of 

 Avater, and anu)ng these the smaller and shallower i)onds are ai)t to 

 sufler more than the larger ones. This danger will be greatest during 

 the months of June and July. 



This condition of affairs is indicated by various signs ; the fish swim 

 about near the surface of the water endeavoring to get a breath of air, 

 they become languid, lose their natural color, and finally perish. If at 

 the first signs of such a catastrophe it is imi)ossible to introduce fresh 

 water into the pond, and if there is no hope of rain, nothing remains to 

 be done but to commence the fisheries at once, and transfer the fish to 

 fresh water. It is true that l)y the fisheries the mud is stirred up, and 

 the water is consequently still more deteriorated, thus increasing the 

 danger, but of two evil.s the smaller one nuist be chosen, and all the fish 

 which can be saved should be saved. Such fisheries, however, should 

 not take place during the heat of the day, but at night. In small ponds 



