﻿MANUAL 
  OF 
  FISH-CULTURE. 
  117 
  

  

  from 
  the 
  direct 
  rays. 
  A 
  pond 
  of 
  this 
  description 
  will 
  accommodate 
  

   10,000 
  lake 
  trout 
  three 
  of 
  four 
  months 
  old. 
  As 
  they 
  increase 
  in 
  size 
  

   this 
  number 
  may 
  be 
  dirainislied, 
  a 
  great 
  deal 
  deiiending 
  upon 
  the 
  

   quality 
  and 
  temperature 
  of 
  the 
  water. 
  

  

  The 
  temi)erature 
  of 
  the 
  water 
  should 
  never 
  be 
  higher 
  than 
  65°; 
  

   preferably 
  from 
  48° 
  to 
  58°. 
  

  

  As 
  when 
  kept 
  in 
  rearing-troughs, 
  the 
  fish 
  are 
  now 
  fed 
  the 
  amount 
  

   they 
  seem 
  to 
  desire, 
  being 
  neither 
  overfed 
  nor 
  starved. 
  Tlie 
  liver, 
  not 
  

   so 
  finely 
  chopped 
  as 
  before, 
  is 
  thrown 
  in 
  with 
  a 
  spoon. 
  At 
  the 
  first 
  

   feeding 
  the 
  fish 
  may 
  be 
  somewhat 
  wild 
  and 
  scatter 
  over 
  the 
  pond, 
  but 
  

   after 
  one 
  or 
  two 
  days 
  they 
  will 
  collect 
  at 
  one 
  point 
  and 
  take 
  the 
  food 
  

   greedily. 
  After 
  four 
  weeks' 
  time 
  they 
  are 
  fed 
  only 
  twice 
  per 
  day, 
  and 
  as 
  

   they 
  increase 
  in 
  size, 
  coarser 
  liver 
  is 
  given 
  to 
  them. 
  Food 
  is 
  thrown 
  

   in 
  slowly, 
  and 
  no 
  more 
  given 
  at 
  one 
  time 
  than 
  the 
  fish 
  can 
  eat, 
  for 
  

   waste 
  matter 
  soon 
  becomes 
  foul, 
  and 
  unless 
  drawn 
  off 
  will 
  speedily 
  

   cause 
  sickness. 
  

  

  In 
  from 
  10 
  to 
  12 
  months 
  after 
  hatching, 
  lake 
  trout 
  artificially 
  reared 
  

   measure 
  from 
  4 
  to 
  8 
  inches 
  in 
  length 
  and 
  are 
  i'ead«y 
  for 
  j)lanting. 
  Tliis 
  

   is 
  done 
  in 
  the 
  same 
  manner 
  as 
  with 
  fry, 
  100 
  fish 
  being 
  placed 
  in 
  each 
  

   can 
  for 
  transportation. 
  

  

  DISEASES. 
  

  

  Tlie 
  diseases 
  to 
  which 
  lake 
  trout 
  are 
  susceptible 
  are 
  those 
  common 
  to 
  

   all 
  other 
  trout. 
  They 
  are 
  caused 
  by 
  impure 
  water, 
  poor 
  food, 
  injuries 
  

   received, 
  and 
  the 
  attempted 
  cannibalism 
  of 
  their 
  neighbors. 
  The 
  first 
  

   three 
  of 
  these 
  causes 
  can 
  be 
  guarded 
  against, 
  but 
  the 
  last 
  is 
  much 
  more 
  

   difftcult 
  to 
  prevent. 
  At 
  the 
  first 
  sign 
  of 
  cannibalism 
  the 
  fish 
  must 
  be 
  

   thinned 
  out, 
  and, 
  if 
  feeding 
  well, 
  transferred 
  to 
  the 
  rearing-pond, 
  where 
  

   they 
  will 
  have 
  greater 
  range 
  for 
  development. 
  In 
  fact, 
  for 
  any 
  of 
  the 
  

   diseases 
  this 
  will 
  prove 
  of 
  more 
  benefit 
  than 
  anything 
  else. 
  

  

  It 
  is 
  beneficial 
  to 
  treat 
  the 
  fry 
  with 
  salt 
  twice 
  a 
  week 
  by 
  shutting 
  

   off 
  the 
  water 
  and 
  sprinkling 
  salt 
  in 
  the 
  trough 
  until 
  a 
  weak 
  brine 
  is 
  

   formed. 
  The 
  fish 
  nuist 
  be 
  watched 
  closely, 
  and 
  as 
  soon 
  as 
  they 
  show 
  

   any 
  signs 
  of 
  "turning 
  up" 
  a 
  full 
  head 
  of 
  water 
  must 
  be 
  turned 
  on 
  

   until 
  all 
  the 
  brine 
  is 
  washed 
  oft', 
  after 
  which 
  the 
  sui^ply 
  may 
  be 
  reduced 
  

   to 
  the 
  regular 
  amount. 
  A 
  small 
  quantity 
  of 
  swamp 
  earth 
  should 
  be 
  

   scattered 
  in 
  the 
  tanks 
  about 
  once 
  in 
  two 
  weeks, 
  merely 
  enough 
  to 
  dis- 
  

   color 
  the 
  water 
  for 
  a 
  few 
  moments, 
  and 
  allowed 
  to 
  wash 
  oft' 
  gradually 
  

   ' 
  with 
  the 
  current 
  of 
  the 
  water. 
  

  

  