Quaglio - Introduction and Diagnostic Overview Flashcards
What is the importance of studying fish pathology?
Ensures the health of fish in aquaculture and ecosystems
Identifies and manages diseases caused by physical, chemical, and biological agents (viruses, bacteria, parasites, fungi)
What are the main causes of fish diseases?
Physical agents, Chemical agents, Biological agents
- Physical agents: Temperature, UV radiation, turbidity
- Chemical agents: Toxic substances, pH changes, ammonia
- Biological agents: Viruses, bacteria, parasites, fungi
What are the key diagnostic steps in fish pathology?
Anamnesis, Signaling, Clinical examination, Sampling, Necropsy and histopathological analysis, Laboratory investigations, Differential diagnosis, Definitive diagnosis
What is anamnesis in fish pathology?
A detailed collection of information about the fish’s environment, history, and health status to determine potential causes of disease
Includes environmental, collective, individual, past, and present anamnesis
What is environmental anamnesis?
Study of water characteristics, Analysis of farming management, Assessment of natural and anthropogenic factors
- Water characteristics: depth, flow, temperature, pH, oxygen, salinity, turbidity
- Farming management: stocking density, hygiene, feeding practices
Why is stress an important factor in fish pathology?
Stress disrupts homeostasis, making fish more susceptible to diseases
Common stressors include poor water quality, overcrowding, and sudden temperature changes
What are common signs of gas bubble disease (GBD)?
Protruding eyes, abnormal swimming, emboli in tissues
- Acute GBD: rapid mortality
- Chronic GBD: embolism in cutis, cornea, and mouth with secondary infections
How does UV radiation affect fish?
Causes sunburn and lesions in areas like the head, back, and dorsal fins
Leads to acute epidermal necrosis in very clear water
What are the impacts of turbidity on fish health?
Affects behavior, respiration, and gill function
- Reduces oxygen levels by warming water
- High turbidity can harm juvenile fish by impairing prey capture
What are the main diagnostic observations during a clinical exam?
Nutritional state, Behavior, Respiratory activity, Skin/eye condition
- Nutritional state: Emaciation, concave abdomen
- Behavior: Erratic swimming, lethargy
- Respiratory activity: Gulping, rolling motion
- Skin/eye condition: Ulcers, exophthalmos
What is signaling in fish pathology?
Records species, purpose, and characteristics
- Species type (warm water or cold water)
- Purpose (fry, ornamental fish, broodstock)
- Age, sex, size
What abnormalities in swimming behavior indicate disease?
Spiral swimming, Swimming near surface, Corkscrew motion
- Spiral swimming: neurological issues
- Swimming near surface: oxygen deprivation
- Corkscrew motion: Whirling disease (caused by Myxobolus cerebralis)
What clinical signs suggest respiratory issues in fish?
Gulping at the surface, Lethargy, Rolling or bell-up motion
How is water quality assessed in fish pathology?
Temperature, pH, Oxygen levels, Turbidity
- Temperature: Cold or warm water species tolerance
- pH: Neutral to slightly basic preferred (6.5–8)
- Oxygen levels: Essential for respiration
- Turbidity: Must be low to avoid stress
What are the lethal temperature limits for fish?
Optimal, Suboptimal, Incipient lethal, Critical thermal
- Optimal: Ideal for growth
- Suboptimal: Outside preferred range but survivable
- Incipient lethal: Near death
- Critical thermal: Causes mortality
How do temperature changes impact fish health?
Higher temperatures reduce oxygen levels and increase pathogen replication, Lower temperatures suppress immune responses, Sudden changes cause stress and vulnerability
How does pH affect fish health?
Optimal pH, Low pH, High pH
- Optimal pH: 6.5–8 for most species
- Low pH (<6): Causes acidosis and gill damage
- High pH (>8.5): Leads to alkalosis and increased ammonia toxicity
What is the significance of dissolved oxygen (DO) for fish?
Critical for respiration and metabolism
Decreases with high temperatures and turbidity; Signs of low DO: surface gulping, lethargy, poor feeding
What are the signs of ammonia poisoning in fish?
Lethargy, gasping at surface, red gills, loss of appetite
Toxicity increases with higher pH and temperatures
What is the importance of biosecurity in fish pathology?
Prevents disease spread within and between aquaculture systems
Includes quarantine, sanitation, and monitoring of water quality
How is sanitation achieved in fish farming?
Removal of organic and inorganic material, Use of drying, sunlight, and chemical disinfectants
What is the purpose of sampling in fish pathology?
Diagnoses diseases based on tissue and organ analysis
Identifies pathological changes early to prevent outbreaks
What is the ideal method for sending samples to the lab?
Transport live fish in aerated plastic bags, Refrigerate dead fish, Fix tissue in formalin
Refrigerate dead fish within 6–12 hours; Fix tissue for histopathology
Why is tricaine methanesulfonate (MS-222) used?
Euthanizes fish humanely during necropsy
Lethal dose: 50–250 mg/L
