OPERATING THE HATCHERY 



gen in a short time. Such devices should 

 only be used as auxiliary equipment or as 

 primary oxygen sources when supple- 

 mented by other sources that are inde- 

 pendent of the truck motor. 



4. When the trip is unusually long and 

 the weather extremely hot. the tempera- 

 ture should be maintained between 65° 

 and 70° F. by periodic icing. When pos- 

 sible, long hauls should be made on cool 

 days. Tanks that are constantly used 

 for long hauls .should be insulated with 

 a 4-ii;ch layer of cork. 



Occasionally the dealer will find it nec- 

 essary to temper minnows as they are 

 being transported from the lake or stream 

 where they were seined. For this pur- 

 pose the truck must be equipped with a 

 small box of ice. The minnow tank is 

 filled with lake or stream water and the 

 aeration pump is adjusted so the aerated 

 water passes over the ice before it re- 

 turns to the tank. Periodically the op- 

 erator will have to stop the truck and 

 take the temperature of the water in the 

 tank. When the water is of suitable tem- 

 perature, the water line to the ice box 

 should be shut off. If the water in the 

 tank is cooled too much or too rapidly, 

 the minnows will develop fatal "frost 

 bites." The water line to the ice box 

 must be equipped with a valve so the rate 

 of cooling can be adjusted. 



Some dealers cool the tank water by 

 using the live box as an ice tray. After 

 the truck tank is loaded with water and 

 minnows the live box full of ice is placed 

 over the top of the tank. The tank water 

 is cooled as the ice melts and drips into 

 the tank. The cooling rate cannot be 

 controlled by this method and more fish 

 suffer from "frost bite" from it than from 

 the ice box. 



5. Salt is a tonic for fish and can be 

 used to help them over the rigors of trans- 

 portation. A salt bath should be given 

 after the trip. When the aeration equip- 

 ment consists of a pump and water jets, 

 salt should not be u.sed in the tank be- 

 cau.se sodium chloride rusts' the ecjuip- 

 inent. 

 0. Truck tanks should never be over- 



loaded, especially during hot weather or 

 on long trips. A load of 9 gallons of min- 

 nows per 100 gallons of water, or 5.6 

 pounds of minnows per cubic foot of 

 water, has been found safe under severe 

 conditions. 



Operating the holding tank 



The bait dealer encounters his 

 greatest loss from handling and 

 holding minnows in the holding 

 tank. Though much of the loss is 

 attributed to fungus disease, the 

 largest part is the direct result of 

 rough handling and careless opera- 

 tion. There is no magic formula 

 for preventing minnow losses. Dis- 

 ease-control treatments will not pre- 

 vent losses due to careless handling, 

 but following the suggestions given 

 here will help to keep losses in bait 

 fishes to a minimum. 



1. Minnows should be handled carefully 

 during seining operations. Dealers who 

 buy their minnows should refuse to ac- 

 cept fish that have been handled roughly. 



2. The minnows should be carefully 

 tempered when they are transferred to 

 the truck tank and again when put in 

 the holding tank (see p. 41 for "harden- 

 ing" process). 



3. The minnows should not be crowded. 



4. Holding tanks should be constructed 

 of wood or smooth concrete, and painted 

 heavily with asphaltum paint. Smooth 

 sides in the tank help prevent disease 

 and injury to the fish. The tank should 

 be deep enough so that the fish are not 

 injured by the jets of water used for aera- 

 tion. The bottom should slope slightly 

 toward the outlet to facilitate cleaning 

 and draining. 



5. Each tank should be supplied with 

 plenty of filtered water — spring water is 

 filtered — and each tank should drain di- 

 rectly to the .sewer without passing 

 through other tanks. The water should 

 enter the tank through pressure jets 



42 



