192 How to obtain it. 
breath. At this time of their existence they are helpless creatures 
indeed. 
When hatched naturally in a brook or in an artificial ova 
bed, the case is very different. They are then amongst the gravel, 
which is the protector which nature gives them from their 
enemies. The hatching box is perfectly clean, and there is, or 
should be, nothing which they can get under. They will very 
soon begin to make up for this by getting under each other, and 
in their efforts to do so will collect in dense masses which have 
been likened to swarms of bees. In fish-cultural language they 
begin to “pack,” and there is no more healthy sign than to see 
all the alevins in a box well “ packed.” 
Many years ago the great idea was to provide some artificial 
“hide” or place for shelter for them, and many devices were 
thought of, but all proved to be great failures. The effect of 
placing a stone or other object in a hatching tank for the fish to 
get under is to provide a place where there is no current, and 
which instead of being beneficial will only prove a “death trap ” 
to a large number of the alevins. By leaving them alone, 
however, a very different result is obtained. Some of them begin 
to feel an instinctive desire to get into a place where the water is 
constantly changing, and having found out by following up the 
current the exact point which best suits them they remain there, 
and others gather to them, and before long they will all be 
densely packed with their heads turned the same way, and their 
noses pointed downwards. 
The sight of from ten to fifteen thousand fish in such close 
proximity to each other might lead one to suppose that many 
would be suffocated, but this never proves to be the case. They 
are perfectly safe as long as they remain packed, but should they 
begin to scatter at too early a stage of their existence, then look 
out for mischief. Whilst packed they are just in that particular 
part of the current which suits them best, and as long as they 
remain there they will take no harm. I am, of course, assuming 
that the water supply will in no way be tampered with just at this 
time. A slight disarrangement of the current will cause the little 
fish to move, or, as one of my men used to put it, to “shift their 
quarters.” And this is better avoided. Too much light is also 
