FISH FEED AND FEEDING OPERATION
CHAPTER EIGHT
FISH FEED
AND FEEDING OPERATION
8.1 FISH FEED MATERIALS
There are two broad classification of fish feed materials.Viz:
1. Natural fish food: These are food found naturally in the
aquatic environment. Fish food also refers to naturally occurring organisms in
water bodies. They are usually called live food. Examples are planktons (e.g
algae, rotifiers, amoeba), earthworms, insects, larvae, maggots, pawpaw leaves
etc
Phytoplankton
ADVANTAGES
OF NATURAL FISH FOOD
1. It provides the constituents of a complete and balanced diet.
2. It help in the development of younger fish.
3. It have high protein and fat content which promote the growth
of fish.
2. Artificial feed: These are processed food materials used to feed
fish. Artificial feed are also called
fish feed i.e artificial formulated / compounded feed obtained through the
combination of ingredients. They usually contain the require nutrients fish
need for proper growth. Examples are artificial formulated feed ( Pelleted and
Unpelleted feeds), rice bran, soybeans cake, groundnut cake, Fish meal, bone
meal, blood meal, wheat bran, cotton seed cake, red oil, garri etc
8.2 TYPES OF FEED
1.
FLAKES: Flakes foods are floating
diets made from fish meal, squid meal, brewers yeast (a source of B vitamin and
protein), soy bean meal, and fortified with vitamins and minerals. They also
haves short lifespan. They are good stayed for top-feeders
2.
PELLETS: pellets are made from a
paste passed through an extruder, cut into cylinders and dried. These are ideal
for large fish that need more substance in their diet. So pellets are made to
float other are made to sink.
3.
CRIPS: Crisp are a low –dust food
that is nutritionally identical to flakes only formed into an extremely thin disc this reduced
waste in the tank also good for most fish.
4.
GRANULES: Granules are like pellets
but smaller they are good for small cichlids, middle- feeders and some bottom
feeders like loaches, most granule sink.
5.
DISCS: Discs are sinking foods
usually plant based and aimed toward sucker mouthed catfish or algae eaters.
6.
LIVE FEED: live feed are just that
alive. They retain all of their original nutrition e.g blackworm, earthworm,
blood worm brine shrimp etc.
7.
MOIST FEED: Moist feed formula contain
many of the same ingredients as other fish food formulas though are broken down
into moist form. Moist feed is often used for feeding baby fish (or fry’ as
they are usually called) since it contains food particles that are small enough
for baby fish to ingest.
8.3 CHARACTERISTICS
OF FISH FEED/ CRITERIA FOR CHOICE OF FEED
1. Durability: Feed should be able to last for some period of time
without losing its values and nutrients.
2. Acceptability: The ability of the fish species to accept artificial
feed.
3. Uniformity: The ability of a feed to provide necessary
nutrients needed for survival of fish.
4. Availability: The feed should be readily available in the
market. i.e not relatively scarce.
5. Digestibility: the feed should be able to digest easily when
eaten by fish.
6. Palatability: This is the properties of feed in which the fish
is willing to eat the feed because of its appearance, smell and taste.
7. Floatability: Ability of
a feed to float on water.
8.4 FEEDING
HABIT OF FISH
Fish can be placed into one of the five groups
depending on the food they prefer to eat.
They can be Herbivores, carnivores omnivores, Limnivores. And filter
feeders
1.
HERBIVORES
FISH:
these are fish that are plant eaters. They do well with staple flake food and
algae wafers. They can also be supplemented with finely chopped lettuce,
spinach, green peas. Example of such fish are , African cichlids and silver
dollars
2.
CARNIVORES
FISH:
these are fish that are meat eaters. These predatory fish may only eat meaty food
such as brine shrimp, tubifex worms, earth worm, and small feeder fish. Example of carnivores
fish are needle fish, and bettas
3.
OMNIVORES
FISH:
these are fish that are both plants and meat eater. Almost all aquarium fish
are omnivores. Their diet should consist of a staple flake food example are
catfish, mollies, crayfish, and goldfish.
4.
Filter feeder: they consume plankton and other
particle present in water. They are usually shellfish such as oysters, clams
and mussels
5.
LIMNIVORES
FISH:
These fish are also known as mud-eater. They feed mainly on algae and on the
microorganisms in your aquarum. These kind of fish are constantly eating, and
can be given pellets and algae based food e.g catfish, synodytis
spp(upside down catfish).
8.5 FEEDING LEVELS OF FISH:
Fish foods (feed) are designed around the way fish
eat, which is why you should know about the shape and placement of the fish’s
mouth. There are 3 feeding levels of fish:
1.
TOP-FEEDERS: They have
an upturned, scoop-like mouth for gathering floating food. They like to feed
off the surface. These includes mollies and platys
2.
MID-WATER
FEEDERS: They have mouth at the very tip of their snouts to gather food
as it falls through the water. These includes tetras, Danios
3.
BOTTOM
FEEDERS: These fishes have mouths on the underside of their snouts to
come in close contact with the bottom. These fish include catfish and coryls
Structure
of fish mouth
NUTRITIONAL REQUIREMENT OF
FISHES:
Feeds and feedstuff contain nutrients and energy sources essentially for fish
growth, reproduction and health. Deficiencies of these substances can reduce
growth rate or leads to diseases and in some cases, excesses can cause a
reduction in growth rate. In fish farming nutrition is critical because feed
represent 40-50% of the production cost. Fish feed requirement can be
established for energy, protein, lipids, minerals and vitamins. These are three
distinct feedlines namely fingerling and production diet.
8.6 COMPOSITION
OF FISH COMPLETE DIET
1.
PROTEIN:- Protein is the most
essential part of fish feed, it is important to accurately determine the
protein requirements for each species and size of cultured fish. There are two
sources of protein in fish feeds, they
are:
2.
ANIMAL SOURCE OF PROTEIN:- meat bone
meal, fish meal, blood meal, liver meal, lung meal, chicken offal meal, feather
meal, termite meal, grasshopper/ locust meal, maggot meal, animals entrails.
3.
PLANT SOURCE OF PROTEIN:- The
protein from this source are low in methionine therefore extra methionine must be added e.g soya beans meal,
cotton seed cake, palm kernel cake, groundnut cake, locust bean seed, brewers
dried yeast.
Protein level in aquaculture feeds generally average 18-20%
for marine shrimp, 28-32% for catfish,
32-38% for tilapia, 38-42% for hybrid striped bass. Protein requirement usually
are lower for herbivorous fish and omnivorous fish than they are for
carnivorous fish and are higher for fish reared in high density (recirculating
aquaculture) than low density(pond aquaculture) system. Protein requirement
generally are higher for smaller fish. As fish grow larger their protein
requirement usually decreases.
1.
FATS (LIPID):- Lipids are
high- energy nutrient that can be utilized to partially substitute for protein
in aquaculture feeds. Lipids supply about twice the energy as protein and
carbohydrates. Lipids typically comprise about 15% of fish diets, supply
essential fatty acid and serve as transporters for fat-soluble vitamin increase
in dietary lipids can help reduce the high cost of diets by partially sparing
protein in the feed, problems such as excessive fat deposition in the liver can
decrease the health and market quality
of fish .
2.
CARBOHYDRATES (STARCHES AND SUGAR):- Are the
most economical and inexpensive source of energy for fish diets. Carbohydrate
are includes in feeds to reduce feed cost and for their binding activity during
feed manufacturing. Dietary starches are useful in the extrusion manufacture of
floating feeds. About 20% of dietary carbohydrate can be used by fish e.g yellow
corn, barley, wheat brain, wheat flour etc.
3.
VITAMINS:- Vitamin are organic
compounds necessary In the diet for normal fish growth and health. They often
are not synthesized by fish and must be supplied in the diet. The two group of vitamins are water soluble
and fat-soluble. Water –soluble vitamins include: B-vitamin, choline, inositol,
folic acid, ascorbic acid (vitamin C) etc. of these, vitamin C probably is the
most important because it is a powerful antioxidant and helps the immune system
in fish. The fat-soluble
vitamin include A vitamins, retinols (responsible for vision),the D vitamins, E
vitamins and tocopherols (antioxidant) and K vitamin such as menadione (blood
clothing skin integrity) of these vitamin E receive the most attention for its
important role as an antioxidants. The most common symptom of vitamin
deficiency is Scoliosis (bent backbone) and dark coloration result from
deficiencies of ascorbic acid and folic acid vitamins respectively.
4.
MINERALS:- Minerals are inorganic
elements necessary in the diet for normal body functions. They can be divided
into two groups (macro-minerals and micro-minerals) based on the quantity
required in the diet and the amount presents in fish. Common macro minerals are
sodium, chloride, potassium and phosphorous. These minerals regulate osmotic
balance and aid in bone formation and integrity. Micro minerals (trace
minerals) are required in small amount as components in enzyme and hormone
systems. Common trace minerals are copper, chromium, lodine, zinc and selenium.
Fish can absorb many minerals directly from the water through their gills and
skin, allowing them to compensate to some extent for mineral deficiencies in
their diet.
8.7 FISH
FEED PRODUCTION MACHINES.
There are many
machine involves in fish feed production, they are as following:
1.
MILLING MACHINE:- Milling
is the machining process of using rotary cutters to remove material from a workpiece advancing (or feeding) in a
direction at an angle with exist of the tool.
2.
FEED MIXERS:- These are
used in feed mills for the mixing of feed ingredients and premixes. The mixer
plays a vital role in the feed production process, with efficient mixing being
the key to good feed production
3.
PELLETING MACHINE:- This is a
machine that make feed stock from loose state into a continuous shape dough,
the resulting paste is extruded through holes in a metal plate.
8.8 FISH FEEDING METHODS
Fish feeding
method is the method of presentation of the feed to the fish. There are three
forms of feeding methods in aquaculture.
I. BROADCASTING:-This involves
scattering of fish feed on pond surface. It is usually done in tanks or pond.
It is equally done on earthen pond when the fish is young. The feed is evenly
distributed on the surface of water. The feed can be blown off by wind. It is
labour intensive.
II.
POINT (SPOT) FEEDING: -It involves feeding of fish at specific point of
the pond. It is commonly practiced in earthen ponds. Fish are easily monitored
using this method. It can aid fish pilferated.
III. AUTOMATIC FEEDING: - It is a mechanical
way of feeding fish. There is proper usage of feed. It is less labour
intensive. It does not involve direct observation of fish.
FEEDING
REGIME Feeding
regime (feeding rates and frequencies) are in part a function of fish size.
Small larvae fish and fry need to be fed a high protein diet frequently and
usually in excess.
FREEDING
FREQUENCY:- This is the number of times fish are feed daily.
Factors
affecting the quantity of feed required by fish
I. Temperature: Fish are cold-blooded
animals and their body temperature depend directly on that of water temperature
to an optimum. Fish feed better at higher temperature than at lower
temperature.
II. Water quality: This affect metabolic
rate. Water with desirable and optimum quality favour higher metabolic rates
and growth of fish, thus requires more feed to meet the metabolic rate. On the
other hand, water with poor quality reduced quantity of feed needed by the
fish.
III. Age of
fish: Fishes at early stage of their life have higher metabolic rates
and at such higher growth rate, therefore require higher quantity of feed at
this stage at more frequent and regular interval. Fish fry may require up to
20% of their body weight as feed while fish fingerling require 10% of their
body weight as feed and adult, 2-5% of their body weight as feed.
IV. Quality
of feed: Fishes accept higher quality feed better than poor quality feed
and at such high quality feed is required more than the low quality feed.
V. Species of fish under culture: The fast
growing species exert pressure on feed and requires more feed. The omnivores
may accept more food than the planktivores.
VI. Standing crop or total weight of fish under
culture: The higher the stocking rate, the higher will be the standing crop
and the more feed will be required in feeding the fish.
HOW TO
CALCULATE THE QUANTITY OF FEED REQUIRED
The quantity of feed required to feed fish daily can be
calculated if the stocking density and the average weight of fish can be
estimated. This can be done by sampling the fish either biweekly or monthly.
The quantity of feeding (f) can be calculate using, F,
=W*S*P
Where F= weight of feed per
hectare in kg, W=weight of fish (kg),
S= stocking rate and
p=percentage body weight.
Example
If an aquaculture has 1000
fingerling o 10g average weight in 1 hectare of fish farm. Calculate the daily
feed requirement at 5% feeding rate
Solution
Weight of feed f,=?
Weight of fish, W,=10g=0.01kg
Stocking rate s,=1000
% body weight, p,=5%=0.05
F=w*s*p=0.01kg*1000*0.5=0.5kg/ha
FEED CONVERSION AND EFFICIENCY CALCULATION
Since feed is expensive and represent 40-50% of the
production cost, feed conversion ration (FCR) or feed efficiency (FE) are
important calculations for the grower. They can be used to determine if feed is
being used at efficient as possible.
Weight of the fish growth
FCR
FCR and FE of
1.5-2.0 and above 50% respectively only are considered good.Fish not completely
efficient (FE of 100% or FCR of 1.0) when fed 10 pounds of feed fish cannot
exhibit pound of growth because they must use some of the energy in feed for
metabolic heat, digestive processing, respiration, nerve impulses, salt
balance, swimming and other living activities. Feed conversion ratio will vary
among species, sizes activity levels of fish, environmental parameters and the
culture system used.
Examples:
(1)Calculate the feed
conversion ratio (FCR), if fish are fed 12 pound of feed and exhibit a 6 pounds
weight gain, and justify the FCR.
Solution: FCR ? ,
weight of the feed to the fish=12 pounds, weight of the fish grow= 6pound.
Weight of the fish growth
6pounds
FCR=2
Since FCR is 2.0 the FCR is
considered good growth for the species of fish.
(2)If fish are feed 10 pounds
of feed and exhibit a 4 pound weight gain calculates the feed efficiency.
Solution: weight of the feed fed to the fish = 10 pound
Weight of the
fish growth =4pounds
Weight of the fish growth
4
FE=
1 = 1 =0.4*100=40%
FER 2.5
STRUCTURE QUESTIONS
1.
The mode of feeding in Nile perch is? (a) carnivorous (b)
filtering (c) herbivorous (d) Omnivorous (e) Sucking
2.
A herbivorous fish feeds are the following except (a) Algae
(b) Moluscs (c) diatoms (d) Grasses (e) Water hyacinth
3. Which of the following fish is a weed eater (a) trout (b) grass
carp (c) catfish (d) pike
4. Excessive nutrient concentration in the oceans give rise to
population explosions of? (a) Phytoplankton (b) zooplankton (c) fish (d)
venomous fish
5. Which of the following is not a live feed for fish (a)
Earthworm (b) brine shrimps (c) mouse (d) black worm
6. Fishes having mouth on the underneath of their snouts are (a)
top feeder (b) bottom feeder (c) filter feeder (d) mid-water feeder
7. Flake food can be made from the following except (a) fish meal
(b) brewers yeast (c) soy beans (d) none of the Another name for mud-eaters is?
(a) Omnivores (b) carnivores (c) lumnivores (d) corylores
8. Overfeeding of fish in a pond can lead to? (a) fouling (b)
pollution of water (c) harmful gases (d) all of the above
9. Feed always used for feeding baby fish are usually in What
form (a)moist (b) flakes (c) pellet (d) granules .
10. The most appropriate
procedure for feeding fish in a pond is to (a) Apply feed at night (b) Stir the
water before feeding (c) Place feed regularly at definite spots (d) Apply the
feed when the temperature is very high.
11. Spot feeding is the best method of feeding (a) Fingerlings (b)
Hatchlings (c) Juveniles (d) Adult fish.
12. An energy yielding ingredient in fish feed is (a) Groundnut
cake (b) Blood meal (c) Bone meal (d)wheat bran.
13. Spot feeding is called
(a) Broadcasting feed on the surface of the water (b) Feeding at 5 hour
interval (c) Feeding of fish at any point at a particular time (d) Feeding of
fish at a particular point and time everyday.
14. How many time a fry should
be fed in a day ? (a) 1-2 times (b) 3-4 times (c) 5-6 times (d) 7-8
times.
15. Fish that feed on other fishes are called (a) Carnivores (b)
Detritivores (c) Herbivores (d) Omnivores.
16. The following are fish feed ingredients of plant origin except
(a) Cassava meal (b) Coconut (c) Fish meal (d) Rice bran.
17. A fish that feeds mainly on plant matter is known as (a)
Detrivores (b) Grazer (c) Herbivores (d) Piscivores.
18. The following are supplementary fish feeds except (a) Blood
meal (b) Hatchery waste (c) Insect larvae (d) Kitchen waste.
19. The following are factors that affect digestion of food in fish
except (a) fish colour. (b} fish health (c) fish species (d) level of feeding.
20. The act of caking mixed ingredients into different sizes is
called (a) bagging (b) drying (c) grinding (d) pelleting.
21. Which of the following ingredients provides carbohydrate for
fish? (a) fish meal (b) insect meal (c) rice husk (d) wheat grain.
22. Which of the following is not a characteristic of fish feed?
(a) digestibility (b) durability (c) elasticity (d) uniformity.
23. The following are types of fish feed except (a)braid (b) crumb
(c) flake (d) moist.
THEORY
1.
List 3 types of fish
feed.
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2.
Mention five factors that affect the growth of fish in pond.
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3.
Mention five factors
that affect feed intake of fish.
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4.
State five characteristics
of fish feeds.
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5. Name two
supplementary fish feed.
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6. Define the following feeding habits in
fish:
(a) Omnivores
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(b) Grazer
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(c) Herbivores
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(d) Piscivores
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(e)Detrivores.
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7. Give three examples each of:
(a) Natural fish food
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(b) Artificial fish feed ingredient.
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8. Give three examples each of the following fish feed ingredients:
(a) Energy yielding
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(b) Protein yielding.
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9. Describe each of the following feeding
methods in fish culture:
(a) Spot feeding
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(b) Automated feeding.
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10. Calculate the daily food requirement, if a farmer has 700 fish
25g average weight in 1 hectare of fish farm at 5% feeding rate.
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