140 FISH FARMING 



addition, the trays containing, the alevins: i.e., the newly- 

 hatched fish may be taken to the washing box, or spare 

 empty hatching box, and therein the alevins can be tho- 

 roughly but gently washed, and all egg-shells removed. This 

 latter is simply done by first raising the tray in the water 

 until the zinc bottom is only just covered with water; 

 then quickly, but gently, depress the tray. The alevins 

 will remain, for the most part, on the bottom of the tray ; 

 the eggs will float, or a large proportion of them will do so, 

 on or near the surface, and they can be skimmed off. In this 

 manner the greater bulk can be removed ; but a few shells 

 are sure to remain, and these may be removed by means of 

 the hand-syphon shown in figs. 39 and 40. Every little bit 

 of shell must be removed. Now is the time, also, to care- 

 fully examine the alevins and remove all weaklings, twins, 

 and other monstrosities : these latter being perfectly useless, 

 and only occupying room valuable for the other fish. Before 

 the trays containing the alevins are placed back in the box, 

 the latter should be thoroughly cleansed, and from the time 

 of hatching until the alevins or fry are transferred outside 

 to ponds, let constant care and attention be given to main- 

 taining perfect cleanliness in the boxes. At the actual 

 time of hatching, as many of the shells should be cleaned 

 out as is possible before the trays are removed for the 

 complete clearance of shells in the washing box. Sometimes 

 it will happen that the eggs in a few trays in different boxes 

 will hatch before the bulk contained in a> box. When this 

 is the case, a, full box of alevins may be made up from trays 

 obtained from several boxes. Note that the first box to be 

 filled with alevins in trays is the one at the head of the row ; 

 this in order to guard against any bits of shell being brought 

 down from boxes in which hatching is taking place above. 



I have said that if attention is paid to the actual require- 

 ments of the hatchery no fear need be entertained of an 

 attack of fungus. This is so. Any neglect will result in 

 the white eggs being attacked by Byssus (Septomitris clava- 

 tus), and the consequent suffocation of the surrounding fertile 



