Fish Flashcards
Key aspects of pet fish
Some worth thousands
2000+ species
Some have demanding environmental & nutritional requirements
Most freshwater species bred for trade
Most saltwater caught in wild
Key aspects of laboratory fish
Third most commonly used animal
Mainly toxicology studies
Increasingly genetic studies
Strict welfare guidelines
Key aquaculture production systems
Ponds
Most commonly used
Enclosed water areas
Least intense
Depends on natural processes
Species: salmonids, tilapia, shrimp/prawns, catfish
Raceways
Single pass system
Require large volumes of water
Rectangular structures
Gravity flow
Species: trout, tilapia, carp, prawns
Cages
Flow through system
Easy stocking, feeding & harvest
Little environmental control
Susceptible to predators
Shared water body – quicker disease spread
Recirculating aquaculture systems (RAS):
Most intensive
Less water required
Significant energy input
Required expertise
Species: salmon, trout, eel, yellow tail
Importance of water quality
Fish in intimate contact with water
Susceptible to poor water quality & sudden changes
Freshwater species often more tolerant to changes than marine species
Aim to provide optimum quality for species
Recirculation systems need sophisticated treatment
Many complicated factors:
Oxygen, carbon dioxide, temperature, ammonia, nitrite, nitrate, pH, salinity, toxins, chlorine
What does low oxygen cause
Low oxygen can cause sudden death
Signs of respiratory disease:
Gasping
Gathering at areas of higher oxygen
Flared gills
What does carbon dioxide cause
Source: fish respiration, decomposing matter
Daily fluctuations opposite to oxygen
Toxicity: high CO2 in water –> fish can’t excrete through water –> CO2 builds up in blood
Describe nitrogen cycle
Ammonia is principal waste product of protein metabolism
Unionised form more toxic
Ammonia is more toxic at higher pH
Broken down to nitrite in nitrogen cycle
Nitrite
From ammonia
Less toxic, low levels can be tolerated
Nitrate
From nitrite
Less toxic, high levels can be tolerated
Converted to nitrogen by plants
Label the diagram and say what each does
Operculum: protective gill cover
Caudal fin: largest & most powerful – forward momentum
Dorsal fin: keeps fish upright & controls direction of movement
Anal fin: additionally helps keep fish stable & upright
Pectoral/pelvic fins: used for steering, balance & moving up/down in water
Lateral line: system of sense organs used to detect movement, vibration & pressure gradients
Describe the internal anatomy of fish
Gastro-intestinal tract
Simple & short in carnivores
Longer in herbivorous fish
Liver
Largest organ
Some fish have hepatopancreas
Kidney
Largest species variation
Can be 2 structures or 1
Anterior kidney – osmoregulation, excretion of waste
Posterior kidney – hematopoiesis, immune function
Gills
Gas exchange
Acid-base balance
Excretion of nitrogenous wastes
Heart
Different shapes & sizes
Receives oxygenated blood from gills & pumps around body
Swim bladder
Not present in all species
Mechanism for maintaining buoyancy & position
What is osmoregulation
Maintenance of constant osmotic pressure in fluids of organism by control of water & salt concentrations
Involves kidney, gut & gills
Immune role
Fill in the osmoregulation table
Factors to consider for home tanks
Number of fish
Species & compatibility
Surroundings/enrichment
Plants – can affect oxygen & nitrogen
Water changes to remove nitrogenous compounds
Differences between salt and fresh water tanks
Outdoor ponds considerations
Stocking density of 2KG per 1000L
Planting
Provides shelter, shade, refuges
Oxygenate
Remove nitrates & phosphates
Oxygen hits lowest point in early hours
Consider surroundings
Describe fish nutrition
Nutritionally appropriate diets in development
Most requirements not known
Reliant on fish meal & oil
Many nutritional pathologies identified
Herbivorous & omnivorous fish:
Less nutrient dense diet
Have long intestine for digestion & absorption
Carnivorous fish:
Often top predators like salmon & tuna
Need nutrient dense, high protein diet
Have short intestine – rapid digestion & absorption
Commercial diets for pet fish
Some live feeds given
Overfeeding often a problem
Describe blood sampling in fish
Tail vein
Ensure lab can do fish
Make some fresh blood smears
