Fish Feed as Nutrition for Fish and
Plants
Kevin Fitzsimmons, Ph.D.
Sec. Tres. American Tilapia Association
Past President – World Aquaculture Society
Professor, University of Arizona
Aquaponics
12 April 2012
Contents
 Nutrition
 Ingredients
and Formulations
 Manufacture and Preparation
 Storage, Handling, and Feeding Methods
Nutrition and feeding behaviours
 Tilapia
are omnivores (eat lots of things)
 Especially capable of consuming decaying
vegetable matter
 Long intestine
 Filter feeders (algae, bacteria, plankton) when
young
 Need protein and balanced nutrition for rapid
growth
 Maybe more cost effective to settle for moderate
growth
Feeding strategy
 Juvenile
fish are especially good at filter
feeding phytoplankton.
 Many hatcheries utilize greenwater culture
 Juveniles also filter feed on small
zooplankters (especially crustaceans)
 Save money on juvenile feeds by partial
nutrition from natural feed in juvenile ponds
and tanks
Tilapia nutrition decisions
 Natural
herbivores and detritivores.
 Opportunistic feeders grazing on algae and
bacteria in production system.
 Fry and fingerlings need high protein
(50-40%) diet
 Growout needs lower protein (32-28%) diet
 “Organic” diets may be needed for “organic”
buyers
 Compare FCR to decide most efficient diet
Minimize fish meal in diet
 Use
more soybean meal
 Utilize other grains treated with phytase
 Increase use of other by-product meals
(meat and bone, blood, feather, poultry byproduct, brewers waste, etc.)
 Examine other locally available ingredients
(rice bran, cassava leaf meal, etc)
Tilapia Biology
 Long
convoluted intestine.
 Digests complex organic matter
 Fry are filter feeders
 Adults are grazers
Proteins
 Tilapia
need balanced set of amino acids.
Basic building blocks of proteins (and
muscles)
 Ten essential amino acids (required)
several more are supplemental
Lipids
 Lipids
are basically fats.
 Fish need a variety of long chain
hydrocarbon fatty acids for proper growth
 Tilapia will also bio-accumulate lipids from
consumed algae
Remember organic chem?
 Found
in many freshwater and marine algae,
canola, walnuts, soybean, and flaxseeds
 Essential part of the nutritional requirement of
almost all organisms
 Important in neural and cardiovascular functions
Facts about fatty acids in other
farmed fish
Fatty acids can also be
elevated in fish
depending on feed
ingredients
 Higher omega-3’s are
expensive and will likely
require higher price

Tilapia - Moderate in PUFA’s:
0.387 g/100g raw
0.600 g/100g cooked
 Tilapia - Moderate omega 3 FA’s:
0.141 g/100g raw
0.220 g/100g cooked
Source – USDA- ARS Lab

Carbohydrates
 Needed
for metabolic energy
 Carbohydrates are polymers of sugar.
 Common ingredients are corn, sorghum,
rice
 Molasses is mostly sugar and water. Does
not supply as much energy as equal mass of
lipid (fat)
Fiber
 Less
digestible material to help move
material though the intestines.
 Helps with micronutrients
Vitamins and minerals
 Commonly
supplied in “premix”
 Often available in natural production of
ponds.
 Not critical for most semi-intensive fish
farm operations.
 Very critical in intensive systems (cages,
raceways)
Pigments
Salmon and trout feeds sometimes include ingredients
that impart reddish or pink color to the flesh.
 Astanxanthin, canthaxanthin and beta-carotene are
commonly used.
 These may be plant or algae extracts, or chemically
derived.
 May also use whole algae as ingredient (Spirulina or
Dunaliella)
 Yes, the same extracts and algae sold in health food
stores, (which was not included in the scare stories)

Binding agents
 Gums,
agar, cooked starches, wheat and
corn glutens, and other ingredients can be
used for binding.
Preservatives
 Ethoxyquin
 Anti-oxidants
 Goal
is to avoid rancidity, loss of nutrients
Attractants
 Fish
oil, fish meal, and fish solubles are
good attractants
Ingredients and formulations
 Normally
need high protein diets for young
 40-50%
 Protein
requirements drop as fish reach
reproductive age. Lipid demand might
increase with egg formation. 30-32%
 Growout diets only need 25% protein
Manufacturing and preparations
Pellet mill
Compression pellet mill
 Feed
mixed with water to dough consistency
 Moistened feed put into hopper, pushed down
to auger screw
 Auger forces feed through the die head.
 Holes in die determine pellet width
 Knife blade cuts pellets to desired length
Extruders
 Floating
feeds
 Feed mixes with steam in barrel of extruder
 Cooks ingredients, improves palatability
 Gelatinizes starches
 Steam expansion and auger forces feed out
of barrel with rapid expansion.
 Traps air in pellet, allows to float
Meat grinders and pasta mills
Bioflocs
 Deliberate
culture of high density of
phytoplankton and bacteria
Storage
 Always
keep feed as dry and cool as possible
 Avoids spoilage and rancidity of fats in diet
 Bags should be on pallets, off floor to allow
air to circulate and slow pests (mice, rats,
roaches, ants, from getting to bags
 Large amount can be stored in bulk in silos.
Handling
 Reduce
rough handling
 Crushed pellets form fines which are not
consumed by fish.
 Fed by hand, blower, belts
Conclusions
 Tilapia
are omnivores
 But eating anything will not make you grow
fast and strong
 Tilapia need balanced nutrition for rapid
growth just like human children