DEVICES FOR USE IN FISH HATCHERIES AND AQUARIA. 



1029 



Water 



A SIPHOID OUTLET FOR HATCHING AND REARING TROUGHS. 



The various systems of outlet in most fish-cultvu'al equipment are defective 

 in several ways, as I have had occasion to observe on visits to different estab- 

 lishments. The young fish escape in the outflow, perhaps, due to its faulty 

 construction or installation ; many of them are caught in the perforations of the 

 sheet-iron cap and die there; many others are killed or injured by the fingers 

 that try to rescue them ; overflows are caused by the clogging of the perforations ; 

 the water is not thoroughly re- 

 newed and the trough becomes 

 infected with germs of disease. 

 All this is too familiar to need 

 to be dwelt upon. I have sought 

 to overcome various difficulties by 

 the following device. 



I have provided a large cylin- 

 drical wire screen or cage, which is 

 set over the outlet and incloses the 

 outlet apparatus which I shall de- 

 scribe. The large surface of the 

 screen gives free course to the 

 water without attracting the yoimg 

 fish and thus becoming a means 

 of their destruction. 



In the daily procedure of 

 changing the water in the rearing 

 troughs, I desire to be able to 

 lower the level to a given point 

 without the necessity of losihg 

 time waiting beside the trough. 

 To accomplish this I have made, 

 first, for the orifice in the bottom 

 of the trough, a water-tight collar 

 of two pieces screwed together 

 with a leather washer between. The lower piece is supplied with lugs extend- 

 ing downward, and into this collar is inserted a tube, making an ordinary 

 standpipe. With this form of outlet, however, the water is renewed only at 

 the surface, the bottom water, with remnants of food, refuse substances, etc., 

 being left unchanged. I have accordingly elaborated the standpipe into a form 

 which constitutes an unfailing cleaning device. It carries off all the solid matter 



Fig. 2. — A siphoid outlet for hatching and rearing troughs. 



