﻿MANUAL 
  OF 
  FISH-CULTURE. 
  77 
  

  

  males 
  are 
  very 
  pugnacious 
  at 
  tbis 
  season, 
  and 
  sometimes 
  fight 
  for 
  an 
  

   hour 
  or 
  more 
  at 
  a 
  time, 
  until 
  they 
  are 
  entirely 
  exhausted; 
  they 
  run 
  at 
  

   each 
  other 
  with 
  open 
  mouths, 
  lock 
  their 
  jaws 
  together, 
  and 
  in 
  that 
  

   position 
  sink 
  to 
  the 
  bottom 
  of 
  the 
  pond, 
  where 
  they 
  lie 
  for 
  a 
  short 
  time, 
  

   each 
  holding 
  the 
  other 
  in 
  his 
  grasp 
  until 
  rested, 
  when 
  they 
  rise 
  and 
  

   resume 
  the 
  combat. 
  As 
  their 
  teeth 
  are 
  abnormally 
  long, 
  they 
  scar 
  

   each 
  other 
  and 
  even 
  bite 
  pieces 
  of 
  skin 
  and 
  flesh 
  from 
  the 
  sides 
  of 
  their 
  

   antagonists. 
  

  

  The 
  males 
  are 
  good 
  breeders 
  at 
  2 
  years 
  old, 
  but 
  very 
  few 
  females 
  

   produce 
  eggs 
  until 
  the 
  third 
  season, 
  when 
  they 
  are 
  from 
  30 
  to 
  36 
  months 
  

   old. 
  At 
  Wytheville 
  hatchery 
  about 
  1 
  per 
  cent 
  of 
  the 
  females 
  spawn 
  at 
  

   2 
  years 
  of 
  age; 
  about 
  50 
  per 
  cent 
  at 
  3 
  years, 
  and 
  about 
  85 
  per 
  cent 
  

   each 
  season 
  after 
  that. 
  About 
  15 
  per 
  cent 
  of 
  the 
  fully 
  matured 
  females 
  

   are 
  barren 
  each 
  season. 
  It 
  was 
  at 
  one 
  time 
  thought 
  that 
  the 
  same 
  

   individuals 
  were 
  barren 
  each 
  year, 
  but 
  experience 
  has 
  shown 
  that 
  

   such 
  is 
  not 
  the 
  case, 
  as 
  fish 
  which 
  were 
  barren 
  one 
  season 
  have 
  been 
  

   held 
  over, 
  in 
  a 
  separate 
  pond, 
  until 
  the 
  following 
  year, 
  when 
  a 
  large 
  

   portion, 
  if 
  not 
  all, 
  produced 
  eggs. 
  This 
  sterility 
  may 
  be 
  the 
  result 
  of 
  

   injuries 
  received 
  during 
  the 
  previous 
  season, 
  during 
  the 
  progress 
  of 
  

   spawning. 
  

  

  EGGS. 
  

  

  The 
  number 
  of 
  eggs 
  produced 
  in 
  a 
  single 
  season 
  depends 
  upon 
  the 
  

   size 
  and 
  age 
  of 
  the 
  fish. 
  The 
  maximum 
  from 
  one 
  3 
  years 
  old, 
  weighing 
  

   ^ 
  to 
  1^ 
  pounds, 
  is 
  from 
  500 
  to 
  800; 
  from 
  one 
  6 
  years 
  old, 
  weighing 
  2 
  to 
  4 
  

   pounds, 
  it 
  is 
  2,500 
  to 
  3,000. 
  The 
  eggs 
  vary 
  in 
  size 
  from 
  4^ 
  to 
  5 
  eggs 
  to 
  

   the 
  linear 
  inch, 
  and 
  are 
  of 
  a 
  rich 
  cream 
  color 
  when 
  first 
  taken, 
  changing 
  

   to 
  a 
  pink 
  or 
  flesh-color 
  before 
  hatching. 
  

  

  THE 
  HATCHING-TROUGHS 
  AND 
  TRAYS. 
  

  

  The 
  eggs 
  of 
  rainbow 
  trout 
  are 
  usually 
  incubated 
  on 
  trays, 
  placed 
  in 
  

   the 
  water 
  in 
  troughs 
  of 
  various 
  sizes 
  and 
  shapes. 
  At 
  Wytheville 
  the 
  

   troughs 
  are 
  set 
  in 
  pairs, 
  as 
  shown 
  on 
  page 
  78, 
  are 
  made 
  of 
  the 
  best 
  

   pine 
  lumber 
  dressed 
  to 
  1^ 
  inches 
  thick, 
  and 
  are 
  15 
  feet 
  long, 
  14 
  inches 
  

   wide, 
  and 
  8 
  inches 
  deep; 
  14 
  inches 
  from 
  the 
  lower 
  end 
  inside 
  is 
  a 
  

   guard-screen 
  of 
  perforated 
  tin 
  or 
  wire 
  mesh, 
  fastened 
  on 
  a 
  frame 
  exactly 
  

   fitted 
  across 
  the 
  trough. 
  Tin 
  with 
  perforations 
  of 
  j-g 
  inch 
  for 
  very 
  

   young 
  fry, 
  and 
  larger 
  ones 
  as 
  the 
  fish 
  grow, 
  is 
  preferable 
  to 
  wire. 
  The 
  

   screen 
  is 
  arranged 
  to 
  slide 
  vertically 
  between 
  beveled 
  cleats, 
  that 
  it 
  

   may 
  be 
  kept 
  clean 
  easier. 
  A 
  plain 
  board 
  3^ 
  inches 
  wide 
  is 
  placed 
  4 
  or 
  

   5 
  inches 
  from 
  the 
  lower 
  end 
  of 
  the 
  trough 
  to 
  serve 
  as 
  a 
  dam. 
  

  

  In 
  the 
  upper 
  end 
  of 
  the 
  trough 
  horizontal 
  screens 
  (B, 
  page 
  78), 
  made 
  

   of 
  perforated 
  tin, 
  are 
  used. 
  These 
  are 
  so 
  constructed 
  that 
  they 
  can 
  be 
  

   slipped 
  forward 
  or 
  raised 
  up 
  (as 
  shown 
  in 
  the 
  illustration) 
  in 
  feeding 
  the 
  

   fry 
  or 
  cleaning 
  the 
  troughs, 
  and 
  the 
  water 
  falling 
  on 
  a 
  small 
  wooden 
  

   block 
  in 
  the 
  center 
  of 
  the 
  screen 
  is 
  thoroughly 
  aerated 
  before 
  entering 
  

   the 
  trough. 
  This 
  arrangement 
  possesses 
  many 
  advantages 
  over 
  the 
  old 
  

   method, 
  where 
  the 
  screens 
  were 
  vertical, 
  or 
  nearly 
  so, 
  as 
  it 
  permits 
  the 
  

  

  