Fish Nutrition Flashcards
What is the most organic material for fish in diet?
Protein
What are the limiting essential amino acids in fish?
Methionine & Lysine
- Limiting amino acids because if not supplied within required limits fish cannot absorb other amino acids
Why do smaller fish require more protein than larger fish?
Need more protein during the growth period - organ and bone development
What is the most expensive component of a fish’s diet?
Protein
Plant sources of protein for fish
Soybean meal
Animal sources of protein for fish
Fish meal - Very expensive (mix with plant sources)
Effects of overfeeding fish:
Waste of money
Increases water pollution
Why dont wont to overfeed protein to fish
It will then use protein as a source of energy which is expensive!!
Only want to use protein to meet growth and health requirements
Not enough protein in fish diet:
Fish will draw protein from non essential tissues
Reduces growth rate
Fish diet: Lipids
High energy nutrients
Supply essential fatty acids (EFAs)
Transporters of vitamins
Cellular membrane
Comprise 15% of fish diets
Why do we want to maximise lipid use in fish diet?
Lipids reduce the amount of protein required for energy
Lowers the cost
Plant sources of lipids for fish
Canola oil, sunflower oil, sesame oil
Animal sources of lipids for fish
Fish oil (best source - more than 30% essential AAs)
Fish diet: Carbohydrates
Most economical source of energy
Help make pellets float
Not essential
Not very efficient
Carbohydrate sources for fish
Cereal grains
Overfeeding lipids to fish
Fat accumulation on liver
Compromises health
Reduces fish shelf life
Overfeeding carbohydrates to fish
Too much fibre in diet (over 8% of diet)
Causes to much fast moving traffic in intestines and fish cant absorb nutrients
Why is the use of carbohydrates limited in cold water fish?
Cold water fish are usually carnivorous and not used to eating carbohydrates
Can feed short chain carbohydrates - easier to digest
Fish energy to protein ration
85 to 110 mg of DP / kcal of DE
Fish energy requirement are a lot lower so the protein to energy ratio gets bigger
Fish don’t need energy to regulate body temp or to convert ammonia to urea
Water soluble vitamins:
B vitamins choline inositol folic acid (vit C) pantothenic acid biotin ascorbic acid
Fat soluble vitamins
A, D, E and K vitamins
Vitamin A
Important of vision
Vitamin D
Important for bone integrity
Vitamin C & E
Important antioxidants in fish
Work together to preserve cells from peroxidation
Vitamin C
Transport of iron in the blood - not enough in diet can lead to anaemia
Antioxidant
Scar tissue formation
Macrominerals
Important for osmoregulation process & bone formation and integrity
Calcium Magnesium Sodium Chloride Potassium Phosphorous
Microminerals (trace minerals)
Important in VERY SMALL amounts for enzyme and hormone systems
Iron Copper Manganese Chromium Cobalt Iodine Zinc Selenium
Fish can absorb many minerals from water
What information must be available in a fish diet?
- Nutrient requirements
- Bioavailable nutrient and energy content
- Minimum and maximum restrictions on concentrations of ingredients
- Cost of ingredients
Types of fish feed
Extruded (floating or buoyant feeds)
- Used to see fish are eating so you know they are healthy
Pressure pelleted (sinking) feeds
Want to feed fish the biggest size pellet that they can eat
