Atypical Aeromonas in Farm-raised Catfish of Mississippi

By
Bradley M. Richardson

What is ‘aquaculture’?

  • Growing/farming of aquatic species
  • Can include plants (e.g. algae) or animals (e.g. fish)
  • Catfish, Salmon, and Tilapia are popular fish species

Aquaculture as an industry

  • Dates back to 6000 B.C. (Australia)
  • Growing 2x faster than meat/livestock since 1980s
  • $120 billion globally
  • Approx. 46% grown for human consumption

Freshwater aquaculture

  • Over half is in freshwater systems
  • Freshwater production dominated by fish
  • Mollusks (clams/mussels) are 2nd most common
  • US expansion began in 1980s; ~65% is fish

Growing pains

  • Waterborne disease and bacterial pathogens
  • Switch from extensive (more ponds, less fish) to intensive (fewer ponds, more fish) practices
  • Sick fish don’t eat; can’t feed medicine

U.S. Catfish Aquaculture

  • 90% produced in MS, AL, AR, and TX
  • MS produces 60-70% alone
    • 213 of 224 MS facilities raise catfish
  • Nearly all fry used in U.S. catfish aquaculture come from Mississippi Delta region

Major diseases in Catfish aquaculture

  • Proliferative Gill Disease (PGD, parasite)
  • Enteric Septicemia of Catfish (ESC, bacteria)
  • Columnaris (bacteria)
  • Motile Aeromonas Septicemia (MAS, bacteria)

Normal Aeromonas hydrophila

  • Ubiquitous around the world, in all water systems
  • Important bacteria for self-purification of water
  • Common pathogen in frogs, turtles, fish, and humans
    • Typically a secondary pathogen (needs weak host)
  • May cause diahrea, rash, or many other symptoms

Atypical Aeromonas hydrophila

  • Believed to originate in Asia
  • First U.S. collection in Alabama (2009)
  • Infections can be chronic to acute
    • 10,000+ kg lost in a few days
  • Clinical signs in catfish include:
    • skin discoloration
    • bulging and hemorrhaging of the eye
    • hemorrhaging/reddening of the fins

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