It is also very convenient if the hatch house contains large and small containers 

 for the spawn trout and for grading food trout. Larger plants also require a packing 

 room and a shipping room. It may also be advantageous to have the food kitchen in the 

 same building as the hatch house and to arrange storage and cooling rooms for the food. 

 Filter arrangements may be placed inside before the level trough, or outside (see Fig. 29) 

 to save space, as freezing oi running water vdll not occur. 



The water lor the hatch house must not be drawn from stocked ponds, in order to 

 avoid Gyrodactylus and other injuries. It is best to draw from an oxygen rich spring 

 brook. If springs and brooks of various winter temperatures are available, it is advis- 

 able to provide a regulation of water temperature. If the brooding water contains much 

 suspended matter such as flakes of iron hydroxide, leaf particles, etc., it must be 

 filtered, especially when hatciiing is done in "self selectors". Formerly, deep walled 

 concrete chambers in whose center a horizontal grate supported a layer of gravel, were 

 used for filtration. The water ran altematel;," through one chamber from above and 

 through the next fro.-n below and finally into the level trough. 



In the fish hatchery of the Eberswalde Forestry School, I liave recently had a filter- 

 ing arrangement constructed (Fig. 29), which has given excellent results. From the 

 storage pond a pipe protected of a sieve on the inlet end leads the water into two pre- 

 filter basins. They are strong rectangular iron vessels, such as are used in industry. 

 The basins are placed on two steel rails which rest on brick pedestals. The basins are 

 wide to provide airiple filtration surface, but not too deep for the best service to the 

 arran^^enent. A wooden grate is set in about 20 cm. above the bottom to hold the filter- 

 ing material, excelsior or gravel. In the pre-filter, coarse gravel is used, and in the 

 filter finer gravel is used. A vertical pipe v/hich opens close to the bottom leads the 

 pre-filtered water into a pipe which conducts it to the three actual filters. Here also 

 the water flows in at the top, so that the top sand layer takes up most of the dirt and 

 can be easily cleaned. Further upright pipes conduct the completely filtered water into 

 the hatch house and into the level trough with overflow, £ach chamber can be cut out 

 separately and drained by an outlet in the bottom. 



The provision of good daylight illumination and a water proof electric lighting 

 arrangement in the hatch house deserves attention, so that all tasks, particularly that 

 of selection, car; be at all times carried out with necessary care. 



FJ.g. 30. LEFT. Living brook trout eggs in eye point stage. 

 RIGHT. 2 dead, v/hite and one moldy dead trout egg, 

 2 X natural size. 



lU 



