﻿CXXIV 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FTSH 
  AND 
  FISHERIES. 
  

  

  to 
  a 
  large 
  number 
  of 
  fishes, 
  young 
  quinnat 
  salmon 
  and 
  young 
  Swiss 
  

   lake 
  trout 
  being 
  the 
  species 
  chiefly 
  affected. 
  The 
  disease 
  in 
  its 
  appear- 
  

   ances 
  and 
  symptoms 
  differed 
  from 
  any 
  previouslj- 
  manifesting 
  itself 
  in 
  

   the 
  local 
  aquaria, 
  and 
  on 
  examination 
  was 
  found 
  to 
  be 
  due 
  to 
  a 
  proto- 
  

   zoan 
  parasite 
  {Ichthyophthirius 
  imdUfiUis 
  Fouquet). 
  This 
  is 
  the 
  same 
  

   animal 
  that 
  produced 
  great 
  mortality 
  among 
  fishes 
  in 
  the 
  Fish 
  Commis- 
  

   sion 
  aquaria 
  at 
  the 
  World's 
  Columbian 
  Exposition 
  m 
  181>3, 
  and 
  was 
  

   there 
  studied 
  by 
  Dr. 
  Stiles, 
  of 
  the 
  Department 
  of 
  Agriculture, 
  whose 
  

   report 
  on 
  the 
  subject 
  is 
  printed 
  in 
  the 
  Bulletin 
  of 
  the 
  Commission 
  for 
  

   that 
  year. 
  It 
  is 
  noteworthy 
  that 
  at 
  Chicago 
  the 
  disease 
  first 
  appeared 
  

   in 
  a 
  lot 
  of 
  catfish 
  {Ameiurus 
  albidus) 
  from 
  the 
  Potomac 
  Eiver. 
  

  

  The 
  parasite 
  thickly 
  covers 
  the 
  entire 
  surface 
  of 
  the 
  body 
  and 
  also 
  

   enters 
  the 
  mouth 
  and 
  gill-cavities 
  and 
  the 
  intestines. 
  The 
  skin 
  becomes 
  

   coated 
  with 
  a 
  thick 
  mucus, 
  the 
  gills 
  are 
  matted 
  together 
  with 
  slime, 
  

   and 
  the 
  gill- 
  coverings 
  bulge. 
  The 
  infested 
  fish 
  abstain 
  from 
  eating 
  and 
  

   remain 
  at 
  or 
  near 
  the 
  surface 
  of 
  the 
  water. 
  The 
  respiratory 
  movements 
  

   are 
  rapid 
  and 
  gasping. 
  Death 
  is 
  gradual 
  and 
  seems 
  due 
  to 
  a 
  combina- 
  

   tion 
  of 
  starvation 
  and 
  asphyxiation. 
  

  

  From 
  60 
  to 
  70 
  per 
  cent 
  of 
  the 
  salmon 
  and 
  nearly 
  all 
  of 
  the 
  trout 
  

   succumbed 
  to 
  the 
  disease, 
  which 
  was 
  arrested 
  in 
  the 
  course 
  of 
  a 
  month 
  

   by 
  thoroughly 
  cleaning 
  the 
  aquaria 
  and 
  filling 
  them 
  with 
  a 
  strong 
  salt 
  

   solution. 
  About 
  the 
  first 
  of 
  May 
  some 
  of 
  the 
  young 
  salmon 
  were 
  

   sent 
  from 
  Washington 
  to 
  the 
  aquaria 
  at 
  the 
  Nashville 
  Exposition. 
  In 
  

   a 
  few 
  weeks 
  the 
  disease 
  appeared 
  on 
  them, 
  but 
  they 
  were 
  killed 
  before 
  

   the 
  trouble 
  had 
  spread 
  to 
  other 
  fishes. 
  Brook 
  trout 
  in 
  the 
  same 
  aqua- 
  

   rium 
  were 
  not 
  attacked. 
  

  

  In 
  the 
  spring 
  of 
  1897 
  a 
  diving 
  beetle 
  (Laccophilus 
  maculosus) 
  appeared 
  

   in 
  numbers 
  in 
  the 
  fish 
  ponds 
  in 
  Washington 
  and 
  proved 
  destructive 
  to 
  

   young 
  bass. 
  Dr. 
  H. 
  F. 
  Moore 
  made 
  some 
  observations 
  on 
  its 
  habits 
  

   and 
  ravages, 
  and 
  found 
  it 
  to 
  be 
  a 
  very 
  dangerous 
  enemy 
  of 
  young 
  fisli, 
  

   which 
  it 
  attacks 
  savagely. 
  Beetles 
  in 
  the 
  larval 
  stage 
  were 
  also 
  dis- 
  

   covered 
  in 
  the 
  bass 
  ponds. 
  Suggestions 
  were 
  made 
  as 
  to 
  expedients 
  

   for 
  iireventing 
  subsequent 
  inroads 
  on 
  the 
  young 
  bass. 
  

  

  