﻿MANUAL 
  OF 
  FISH-CULTURE. 
  79 
  

  

  Four 
  liatohing-trays 
  are 
  placed 
  in 
  each 
  trough 
  and 
  are 
  secured 
  by 
  

   keys 
  or 
  wedges, 
  and 
  should 
  be 
  from 
  1 
  to 
  2 
  inches 
  lower 
  at 
  the 
  end 
  next 
  

   to 
  the 
  head 
  of 
  the 
  trough, 
  as 
  shown 
  at 
  D, 
  D, 
  D, 
  D, 
  page 
  78. 
  If 
  placed 
  

   in 
  this 
  way, 
  each 
  tray 
  will 
  hold 
  from 
  12,000 
  to 
  15,000 
  eggs 
  with 
  safety. 
  

   Muddy 
  water 
  daring 
  the 
  hatching 
  season 
  necessitates 
  the 
  use 
  of 
  a 
  tin 
  

   tray 
  with 
  a 
  perforated 
  bottom 
  (shown 
  at 
  E, 
  page 
  78), 
  which 
  is 
  13^ 
  inches 
  

   wide 
  and 
  32 
  inches 
  long. 
  This 
  sets 
  inside 
  of 
  the 
  hatching-trongh 
  on 
  

   feet 
  raising 
  it 
  an 
  inch 
  above 
  the 
  bottom 
  of 
  the 
  trough. 
  The 
  hatching- 
  

   tray 
  containing 
  the 
  eggs 
  is 
  placed 
  inside 
  and 
  rests 
  on 
  the 
  brackets 
  

   shown 
  at 
  G. 
  The 
  fish, 
  as 
  they 
  hatch 
  ont, 
  fall 
  from 
  the 
  hatching-tray 
  

   upon 
  tlie 
  jjerforated 
  bottom 
  of 
  the 
  tin 
  tray, 
  and 
  by 
  their 
  movements 
  

   work 
  the 
  sediment 
  through, 
  leaving 
  them 
  on 
  a 
  clean 
  bottom 
  and 
  in 
  no 
  

   danger 
  of 
  being 
  smothered. 
  The 
  tin 
  trays 
  are 
  also 
  useful 
  in 
  counting 
  

   fish, 
  or 
  in 
  holding 
  small 
  lots 
  of 
  fish 
  of 
  different 
  si)ecies 
  in 
  the 
  same 
  

   trough. 
  Where 
  supplementary 
  trays 
  are 
  not 
  used, 
  the 
  fry 
  fall 
  directly 
  

   into 
  the 
  troughs. 
  

  

  Troughs 
  15 
  feet 
  long 
  will 
  admit 
  of 
  four 
  hatching- 
  trays 
  in 
  a 
  single 
  

   row, 
  each 
  of 
  w^hich 
  will 
  safely 
  carry 
  12,500 
  eggs, 
  making 
  50,000 
  to 
  a 
  

   trough; 
  this 
  is 
  enough 
  to 
  work 
  easily, 
  but 
  if 
  it 
  is 
  necessary 
  to 
  make 
  

   more 
  room 
  a 
  double 
  row 
  of 
  trays 
  may 
  be 
  put 
  in, 
  one 
  tray 
  resting 
  on 
  

   the 
  top 
  of 
  the 
  other. 
  Thus 
  the 
  trough 
  could 
  contain 
  100,000 
  eggs 
  as 
  

   its 
  full 
  capacity. 
  The 
  troughs 
  will 
  carry 
  this 
  number 
  up 
  to 
  the 
  time 
  

   of 
  hatching 
  by 
  placing 
  the 
  trays 
  lower 
  at 
  one 
  end 
  than 
  the 
  other, 
  as 
  

   previously 
  described. 
  

  

  When 
  the 
  hatching 
  stage 
  arrives, 
  two 
  trays 
  of 
  12,500 
  eggs 
  each 
  are 
  

   as 
  many 
  as 
  should 
  be 
  left 
  in 
  one 
  trough 
  ; 
  with 
  this 
  number, 
  by 
  using 
  the 
  

   horizontal 
  sliding-screen 
  in 
  the 
  upper 
  end, 
  there 
  is 
  but 
  little 
  danger 
  of 
  

   the 
  alevius 
  congregating 
  and 
  smothering 
  in 
  any 
  part 
  of 
  the 
  trough. 
  If 
  

   it 
  is 
  necessary 
  to 
  hatch 
  a 
  much 
  larger 
  number 
  than 
  this 
  in 
  one 
  trough, 
  

   the 
  sliding-screen 
  is 
  so 
  arranged 
  that 
  the 
  water 
  falls 
  well 
  up 
  against 
  

   the 
  end 
  of 
  the 
  trough. 
  This 
  is 
  done 
  by 
  raising 
  the 
  screen 
  and 
  turning 
  

   it 
  back 
  against 
  the 
  reservoir, 
  or 
  by 
  putting 
  in 
  a 
  wedge 
  shaped 
  block 
  for 
  

   the 
  water 
  to 
  fall 
  upon, 
  turning 
  the 
  thin 
  side 
  of 
  the 
  block 
  toward 
  the 
  

   upper 
  end 
  of 
  the 
  trough. 
  Fifty 
  thousand 
  trout 
  have 
  been 
  hatched 
  in 
  

   one 
  trough 
  prepared 
  in 
  this 
  way 
  without 
  loss 
  from 
  suffocation, 
  but 
  it 
  is 
  

   not 
  advisable 
  to 
  hatch 
  such 
  a 
  large 
  number 
  together. 
  

  

  The 
  amount 
  of 
  water 
  necessary 
  for 
  hatching 
  and 
  rearing 
  depends 
  

   upon 
  the 
  temperature 
  and 
  the 
  manner 
  in 
  which 
  the 
  water 
  is 
  ap])lied. 
  

   The 
  water 
  should 
  receive 
  as 
  nmch 
  aeration 
  as 
  possible 
  before 
  entering 
  

   the 
  compartments 
  containing 
  the 
  fish 
  and 
  eggs. 
  At 
  Wytheville, 
  where 
  

   there 
  is 
  an 
  even 
  temperature 
  of 
  water 
  of 
  53° 
  in 
  the 
  hatchery, 
  about 
  the 
  

   following 
  quantities, 
  are 
  used 
  in 
  the 
  troughs 
  containing 
  fish 
  and 
  eggs: 
  

  

  100,000 
  pggs 
  during 
  incubation, 
  12^ 
  gallons 
  per 
  minute. 
  

   100,000 
  fisli 
  Latching 
  to 
  time 
  of 
  feeding, 
  .30 
  gallons 
  per 
  minute. 
  

   100,000 
  fish 
  from 
  1 
  to 
  4 
  months 
  old, 
  .50 
  gallons 
  per 
  minute. 
  

   100,000 
  fish 
  4 
  to 
  6 
  months 
  old, 
  100 
  gallons 
  per 
  minute. 
  

   100,000 
  fish 
  from 
  6 
  to 
  12 
  months 
  old, 
  200 
  gallons 
  per 
  minute. 
  

  

  