CONTINUATION

• Topics to be included in long quiz

  • Special senses
  • The endocrine system
  • Nervous system
  • General habitat management
  • Fish pharmacology and therapeutics
• Fish pharmacology


  Essential for undertaking treatment of fishes using any therapeutic chemicals or drugs

  
• Factors to consider before recommending any medicine to treat fish diseases

  • Water quality
  • Pathogens
  • Fish mortality rate
  • Legal issues
  • Economics of treatment
• Drugs


  (according to WHO in 1966) Any substance or product which is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient
• Methods of drug administration and application

  • Enteral
  • Parenteral (injected)
  • Topical
• Oral administration


  Administration of drugs through the mouth, less wasteful method than water medication
• In-feed medication


  Standard practice for a large number of diseases but it is actually prophylactic not therapeutic
• Medicated feed


  Pellet form either of floating or sinking variety, thrown upon the surface of the water, a process termed broadcasting feeding

  
• Drugs used in feed medication

  Antibacterial & Anti parasitic
• Oral administration is useless for mature adult anadromous fish such as salmonids returning to freshwater to breed, as these too do not feed
• The efficacy of any oral administration depends on the drug concerned not being digested before absorption
• Gavage


  A form of oral administration extensively used in experimental work, rarely used in routine fish management as it is labour intensive and stressful to the fish

  
• Immersion or Dipping


  Preparation of a small volume of medicated water in a separate container, the fish, usually held in a net, are immersed for a short period of time and then returned to their normal environment
• Freshwater Dip


  (for saltwater fish only) Rids the fish's body of many potential harmful parasites such as Paravortex, Cryptocaryon, and Velvet
• Saltwater Dip


  (for freshwater fish only) Relieves fish stress and aids the organism in fighting off diseases, the concentration should be 4 teaspoons per Gallon and the duration of the bath about 30 minutes
• Salt bath


  Effective in removing Protozoa (one celled parasites) on skin, gills, and fins, however some fish do not respond well to a salt bath
• Bath Treatment


  Differs from a dip in that it requires a prolonged treatment time, tarpaulins are placed around the cage, separating the contained from the surrounding water and the drug is added, preferably at several points in the bath to ensure rapid mixing
• Formalin


  Used as a bath to rid external parasites, works by altering cell proteins
• Malachite Green


  Rids the fish of all fungal infections, a respiratory poison that damages cell metabolism
• Formalin and Malachite Green


  Often used in combination as they increase the benefits of each other and are less toxic than if used separately
• Methylene Blue


  Effective against skin and gill flukes, ick, velvet, fungus and many external parasites and bacterial infections, works by staining cells and disabling their metabolism
• Potassium Permanganate


  Eliminates anchor worms, fish lice, flukes, ick, cotton mouth, fungus and many bacteria
• Flushing


  Method where fishes are kept in running water or a raceway system, wherein immersion can be achieved through flushing, more wasteful and environmentally polluting than dipping, drawback is to obtain a homogenous distribution of the medication in water

  
• Hyperosmotic Infiltration (HI)


  Development of immersion designed to accelerate the absorption of macromolecules or even of particles such as antigenic bacteria, involves two separate immersions in a pharmacologically inert hypertonic solution followed by the medicine or vaccine solution
• Purposes for parenteral injection

  • Vaccination
  • Treatment of limited number of valuable fish with drugs which cannot be given by other route of administration
  • The 'Hormone and Heat stress" diagnostic procedure for salmonid smolt to check for "stress inducible furunculosis" (SIB)

  
• Sample characteristics for disease investigation and diagnostic purposes

  • Representative of a population, including different stages of the disease
  • Includes healthy fish for comparison
  • Freshly dead fish (2-4 hrs after death as maximum)
  • Varies according to age, size, suspected disease (1-5 fish for acute toxicity, 10-15 small fish or 5-10 large fish for infectious diseases)
• Sign of freshness: Encysted Metacercaria (EMC)