Fish Nutrition 101:
Feeds and Feeding
Laura Tiu, Ph.D.
OSU South Centers
Piketon, Ohio
Fish Nutrition 101
The objective of feeding fish
• provide the nutritional
requirements
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good health
optimum growth
optimum yield
minimum waste
reasonable cost so as to
optimize profits
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Why so important?
The feed that determines
• Economic viability of the enterprise
• 60-70% of variable production costs in a
normal production cycle is due to feed.
• Fish growth rate
• Health status of the fish.
• Nutrient loading (and ultimately carrying
capacity) in the pond or tank
• Water quality within the culture system
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Unique Fish Nutrition
Fish have a low body maintenance requirement.
• Fish are cold-blooded:
• Floating in the water consumes less energy than
standing and walking on legs.
Fish feeds are also more concentrated than those for pigs
or cattle, since they do not need ‘filler’ ingredients such as
fiber.
Fish use oils and fats as their prime energy source - more
concentrated than the carbohydrates needed by land-living
animals.
Most fish are carnivorous while most farmed land animals
are basically herbivorous
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Feed/Nutrition
Use high quality feed.
Feed must provide complete nutrition with
maximum conversion efficiency.
Extra protein is needed to ensure rapid
growth without reducing water quality.
Lower quality feeds often have poorer
conversion efficiency, which results in more
waste products.
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Feed Quality
The quality of feed refers to the nutritional
as well as the physical characteristics of
the feed that allow it to be consumed and
digested by the fish.
Protein - Balanced mix of amino acids builds
muscle
Fat -Provides dense energy for metabolism
Oxidizes rapidly – becomes rancid
Carbohydrate - Fish can only digest simple
sugars
Vitamins & Minerals - Included in mixed
rations
A good pellet is a package of complete diet!
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Feed Quality - Physical
The physical attributes of the feed determine
the degree to which the feed affects water
quality and consumption rates by the fish.
• ingredients finely ground, uniform color
• without fines or dust
• water stability of at least 30 minutes
• floating or sinking
• correct size so the fish can swallow them
• palatable with a good taste, smell and feel 7
Selecting a feed
Know the nutritional requirements of species
Feed the proper form and size
Study fish feeding behavior
Keep good records
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Feed Conversion Ratio
The measure of an animals efficiency at converting
pounds of food to pounds of body mass.
Examples:
Cows 8:1, 8 lbs of food for 1 lb meat gain
Pigs 4:1
Chickens 2:1
Fish
Tilapia 1.7:1
Atlantic Salmon 1.2:1
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Feeding strategies
Satiation - all the feed the fish will eat daily (time
consuming)
Body Weight - based on estimated fish weight (3% - 5% of
fish body weight per day)
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Factors that Affect Feeding Behavior
Dissolved oxygen below 4.0 ppm
Cool or hot water temperatures
Changes in pond water level
Disturbance by seining, etc.
Disease
Presence of aggressive fish
Time of day
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Feeding Strategies
Spread feed evenly
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Important to scatter feed over as much of
the pond as possible
Aggressive, larger fish will "hog" the feed
and reduce feed efficiency
If your feed application system is limited
to a small area of the pond, divide the
feed into two or more feeding passes
Fish will learn your feeding patterns, so
occasionally reverse or alter your pattern,
to provide an opportunity for all fish to
obtain feed
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Feeding strategies
Avoid overfeeding
• When consumed feed isn't efficiently
converted into tissue, the fish are overfed
• FCR in fish goes down when they eat more
than necessary for optimal growth
• When fish are overfed, these additional waste
products stimulate the development of large,
unmanageable plankton populations
• Nutrient and/or oxygen requirements of one or
more of the populations may exceed the
supply rate, resulting in a crash
• Nutrient concentrations may reach toxic levels
before these populations can recover. Aeration
and therapeutants may be required to limit the
onset of fish disease or mortality
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Assessing Feeding Response
In order to make this assessment, the following should
be noted by the farmer during feeding:
• How fast the fish moved towards the feed and how this
reaction/behavior compares with that at previous feedings?
• Whether or not the fish are interested in the feed?
• What the color of the pond water is prior to feeding?
• What proportion of the fish comes to the feed?
• What the weather was a few days before, and on that day? Is
(was) it rainy, cold or hot?
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Adjusting the Ration
Feeding rations should be adjusted either
weekly or fortnightly depending on the fish’s
size.
• Use feeding chart
• Sampling monthly
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When NOT to feed fish
• The feeding response is poor
• They are feeling unwell
• At least two days before harvest or
transportation
• The afternoon before sampling and on the
sampling Day before sampling
• When treatments are applied to the pond
• When water temperatures are low or rainy days
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Feed Records
Records about feed usage should indicate:
• type of feed(s) administered,
• amount of feed given each day,
• feeding response at each feeding,
Records will
• assess cost-effectiveness
• keep track of fish inventory
• project annual production
• calculate cost per pound of production
• Software programs helpful
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Ordering Feed
Don’t wait until the last minute
• Two weeks needed for Purina
Ask about feed costs and transportation
costs
Get several quotes
Try to cooperate with other farmers
Buy only what you need and can store
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Food Storage
Keep cool – slows oxidation
Keep dry – prevent mold growth
Keep covered-prevents rodents and bugs
Keep fresh – 3 months barn, 6 mos. cooler
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Can I make my own feed?
Not practical or economical on a large scale
• Can’t float
• Difficult to get high quality
University of Florida Extension fact sheet
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Summary
Use a good feed
Feed the correct form and size
Feed according to fish behavior
Keep good records
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