Fish Husbandry Flashcards
Different categories of fish
Pet fish - marine, tropical, freshwater, cold water
Fish farms - trout, salmon and coarse fish
Commercial fisheries - angling clubs
Main parameters in water quality and what they should be
Dissolved Oxygen - should be 6-7g/ml
^ most critical, first indication of low is lethargy and inappetence
pH - 6.5-8.5 for freshwater, 8.1-8.4 for marine
temperature - wide range, 24-27 degrees for tropical
ammonia - fish release ammonia as nitrogenous waste through the gills. if there is already high ammonia in the external water, they cannot excrete and so the ammonia leaks into the blood, affecting the blood pH and preventing the animal from taking in oxygen
nitrite - harmful to fish by causing “brown blood disease”
nitrate - presumed to be not particularly harmgul
alkalinity - 100mg per litre
salinity - marine salt only, 35ppt
How does biological filtrate work ?
recirculating the water to exploit the nitrogen cycle and oxidise ammonia into the less harmful nitrate
water -> solid filtration -> biofiltration -> CO2 removal -> pumping -> disinfection -> heating and cooling -> fine particle removal -> pH control -> oxygenation -> return to tank
Types of filtration systems
undergravel - not good, lead to most fish deaths due to ammonia build up
activated charcoal - seen in fresh water, show mineral absorption techniques
spray bar - seen in marine, oxygenates water as it enters, providing bacteria with nutrients to break down ammonia
aquatic plants - seen in fisheries, natural ammonia degradation with plants
Fish Nutrition key points
juvenile fish need ~5% BW
adults need ~2%
natural environment may change appetite (e.g. temperature) - don’t need to feed every day
feeding to correct size of fish very important
storage of food important to prevent micro-toxin production and development
Non-infectious Reasons of Fish death
bad water quality - fish produce a lot of mucus, leading to lamellar hyperplasia where the gills clump together to try and protect themselves
transportation - cumulative stress, especially if in transit
wild capture - destructive, especially with more controversial methods (i.e. cyanide or explosives)
cultivating tropical species and illegal importation
Infectious diseases
fish aren’t researched
not a lot of knowledge
mainly bacterial
Parasitic diseases
fish get a wide variety
nematodes known
associated with stress
fish euthanasia
correct and legal method is overdosing with an anaesthetic. stunning and stopping the heart or a sharp blow to the head are also accepted methods
legally, a fish must be pithed to ensure death
unacceptable methods include releasing into the wild, flushing down the toilet and freezing.
