66 U. S. BUREAU OF FISHERIES. 
TUPELO (ttss. ) STATION. 
[Davip Dayins, Superintendent. ] 
The output of this station for the year consisted of 405,500 large- 
mouth black bass, 73,005 sunfish, and 1,280 crappie, and the distribu- 
tion was extended to approximately 310 applicants, located in Mis- 
sissippi, Alabama, Tennessee, Arkansas, Louisiana, and Kentucky. 
The station output was also supplemented by a carload shipment of 
miscellaneous fishes from the rescue field on the upper Mississippi 
River, consisting of crappie, catfish, rock bass, buffalofish, carp, and 
yellow perch, all of which entered into the general distributions. , 
Of possible interest in connection with pond fish culture was the 
unusually late spawning of the largemouth black bass this year. 
On August 19, 1921, a lot of 3,000 advanced largemouth black-bass 
fry were taken from one of the station ponds, and again, on Sep- 
tember 28, another lot of the same species and size was obtained. 
PRACTICAL DEVICES FOR USE IN POND FISH CULTURE. 
A PRACTICAL SYSTEM OF CLEANING FISHPONDS. 
The necessity for the frequent cleaning of ponds in which fish 
are retained under artificial conditions is well known. If the ponds 
are of cement or lumber construction, the usual method of cleaning 
is to lower the water level and scrub the sides and bottom of the pond 
with a suitable brush. During the cleaning process the water in the 
pond becomes turbid and polluted from stirring up the accumulated 
sediment and filth from the bottom of the pond. The fish are forced 
to endure this unnatural condition until the pond is scrubbed, the 
accumulation of sediment flushed out through the outlet, and the pond 
again filled with clear water. In addition to this unfavorable condi- 
tion to which the fish are exposed they are subject to further possible 
injury by bruises from contact with the brushes used in the scrub- 
bing process. These conditions are entirely unavoidable under the 
system of cleaning in general use. 
At the Manchester (Iowa) station a system of cleaning ponds that 
successfully overcomes both these difficulties has been adopted. (See 
Fig. 2.) At this station there are eight stock ponds of cement con- 
struction. They are approximately 80 by 13 feet and are 3 feet deep 
at the outlet, the bottom sloping upward toward the inlet, where the 
depth is 24 feet. 
For the proper cleaning of the ponds a cement wall or dam, ex- 
tending into the pond 44 feet from each side, is installed, leaving a 
4-foot opening in the middle. This dam is placed 20 feet from the 
inlet end of the pond and is 1 foot high. The open ends are 
grooved to accommodate a dam board 2 inches in thickness. In 
cleaning the pond the water level is lowered until that portion of 
the pond bottom between the inlet and the division wall is just covy- 
ered. The pond being deeper at the outlet end, there is still sufficient 
water to hold the fish safely while the other section of the pond is 
being cleaned and flushed. After cleaning the first section the water 
is permitted to rise until the division wall is about submerged. The 
fish are then driven through the 4-foot opening in the wall into the 
clean section of the pond by the use of a “ push screen.” <A board 
