DISEASE & PEST MANAGEMENT [objectives] Explain aquaculture diseases and pests and how they cause problems Discuss how fish show signs of disease Explain diseases and how they are managed Explain parasites and how they are managed Explain predators and how they are managed Describe trash fish and the problems they cause Explain what to do if fish appear unhealthy Discuss regulations in disease and pest control

AQUACULTURE DISEASES AND PESTS – chapter 6 A disease is a condition that develops in an organism and then damages it in some way. A pest is a plant, animal, or other organism that is detrimental to a species. Aquacrops need a healthy environment; one that is free from diseases and pests. Diseases and pests cause losses.

EXAMPLES

KINDS OF LOSSES Direct losses occur when aquacrop is attacked or injured. Water birds and predators (eat crop) Diseases (reduce growth or death) Parasites (reduce growth, produce stress) Poaching (theft by humans)

KINDS OF LOSSES Indirect losses result in less than ideal environments. Weeds (make harvesting difficult) Trash fish (compete for food and oxygen) Rodents or other burrowing animals (may cause water leaks)

SIGNS OF DISEASE IN FISH (SYMPTOMS) Not eating (going off the feed) Skin abnormalities (ulcers, lesions, abscesses) Lack of vigor (sluggish, drooping fins) Abnormal body shape (growths, swollen belly, bulging eyes) Behavioral change (rubbing, gulping) Dead fish

KINDS OF DISEASES Infectious diseases – may be transferred from one individual to another (examples – bacterial infections, fungal and viral diseases, parasite infestations) Noninfectious diseases – not transferred from one individual to another (examples – nutritional, environmental, chemical and physiological disease)

INFECTIOUS DISEASES Fungal Bacterial Parasitic fish lice Viral

NONINFECTIOUS DISEASES Nutritional diseases – inadequate diet Environmental diseases – water gases, improper temperatures and water quality Chemical diseases – contaminants such as pesticides or heavy metals Physiological diseases – organ malfunctions from sudden changes

DISEASE CONTROL Prevention – the practice of keeping aquacrops healthy and disease free Sanitation – practice of keeping water and facilities clean Quarantine – isolation of aquacrops not known to be disease free from those that are

DISEASE TREATMENT Dipping – immersing fish in concentrated medication Feeding – using medicated feed Bathing – similar to dipping but less concentrated for longer period of time Injecting – only for fish large enough to hold Indefinite treatment – low dose of medication added to tank or pond

PARASITES AND THEIR CONTROL Ectoparasites (external) – found on skin, gills, or fins Endoparasites (internal) – live in organs, flesh, or digestive tract Examples – tapeworms, flukes, leeches, roundworms, protozoans, crustaceans.

PARASITE CONTROL Quarantine - isolation Treatment of facilities – dry ponds and sterilize Dipping – salt solution, formalin Bird elimination – birds often transfer parasites Indefinite treatment

PREDATORS AND THEIR CONTROL Birds – cormorants, kingfishers, herons, grebes, and mergansers Fish – some prey on other fish, some prey on eggs Snakes – do not eat large amount of fish Insects – can destroy eggs or fry Turtles and alligators – usually only eat trash fish (gars, carp) Bullfrogs – eat fingerlings (crawfish, too!)

BIRDS

FISH, SNAKES,INSECTS, BULLFROGS