Aquaculture is the farming of aquatic plants and animals in controlled
environments. Finfish and shellfish are grown in artificial containers such as
earthen ponds, cages and concrete or fiberglass tanks. The cultured organism
is reproduced and offspring raised in captivity. The young organisms are
stocked at a known density and fed a nutritionally complete diet to maximize
growth rate. Water quality is monitored to maintain a healthy environment.
Animals are harvested with nets when they reach market size.
Aquaculture includes culture of fish, crustaceans, molluscs etc.
Types 1. Freshwater includes cold water fisheries
2. Brackish water- cultivation of seabass, mullets, shrimp etc
On the basis of management 1. Extensive
• Cultivable fish species are Trout (Brown &
rainbow trout), Indian trout (Schizothorax
spp), Mahseer, Common carp including mirror
carp among cyprinidae.
• Modern trout farms in India – Himachal
Pradesh trout farm, J & K trout farm.
• The potential cultivable species have gained
importance due to excellent food value,
delicious taste, better meat quality and
Ponds & tanks – 2.25 million ha
Beels & derelict waters – 1.3 million ha
Lakes & reservoirs – 2.09 million ha
Irrigation cannals & channels – 0.12 m Km
Paddy field – 2.3 million ha
Considering the availability of water area of
ponds & tanks only 45% utilized shows the
potential of horizontal expansion
• FW aquaculture account over 70% of total
inland fish production.
• Both Indian and exotic carp contribute over
90% of total freshwater aquaculture
•FFDAs enhanced the average productivity
from 500 to about 2000 Kg/Ha/yr however the
potential of technologies is 15 tonnes/Ha/yr.
Sl. No. Culture system Average production
1 Composite fish culture 4-6
2 Intensive culture 10-15
3 Clarias culture 3-5
4 Sewage-fed fish 3-5
5 Integrated fish 3-5
6 Pen culture 4-5
7 Cage culture 10-15
8 Running water fish 25-50 kg/m3
9 Shrimp farming 2-5
10 Aquatic weed based 3-4
11 Biogas slurry based 3-5
12 Makhana & air breathing fish 1.52 + 94 kg makhana
Fish production range under different culture systems
Culture of Indian Major Carps
Management of Nursery Ponds
Pond may be either existing one or newly constructed
The shape of pond must be rectangular . Size of pond should be
0.03 to 0.05 ha with water depth of 1 to 1.5 m. It is necessary to
expose pond bottom to the sunlight for better mineralization,
escape of toxic gases and to keep free from aquatic insects,
aquatic weeds, predatory fishes.
1.Eradiation of aquatic weeds.
2.Removal of unwanted fish.
3.Application of lime.
5.Control of aquatic insects.
1. Aquatic weeds
It is defined as unwanted and undesirable vegetation that grow in waters
and if unchecked causes serious problems in fish culture.
Based on the habitat, classified into floating, submerged, emergent,
marginal, filamentous and algal blooms.
a. Floating weeds – Don’t have roots, they may be floating in water with
leaves over surface of water, drifted by water currents and waves
induced by winds. They are more problematic than the other kind of
weeds. Eg. Eichhornia (Water Hyacinth), Pistia (Water Lettuce),
Salvenia (Water Fern), Duck weed (Lemna, Azolla, Spirodella)
b. Submerged weeds – Present in water column and not seen above
water surface, some are rooted at the bottom of the ponds while
some are non-rooted. Rooted weeds – Hydrilla, Vallisneria (Tape
grass), Potamogeton, Otelia, Najas, Chara (Stone wort), Non-rooted –
c. Emergent weed - Rooted at the pond bottom but leaves are floating
above surface of water. Eg. Nymphia, Nelumbo, Nymphoides,
d. Marginal weeds – They are grown at edge of ponds or at interphase
between land and water, grow over moist land. Eg. Typha, Marselia,
e. Filamentous algae and algal blooms – Scum or mat forming type and
found floating at pond surface. Eg. Spirogyra.
Algal blooms are formed by unicellular algae. Eg. Microcystis,
Euglena.They are formed due to over fertilization or due to input of
Disadvantages of aquatic weeds
• Interference in culture activities.
• Decrease in DO level
• Restrict space for movement of fish.
• Utilize nutrients.
• Interference in netting operation.
• Restrict light penetration.
• Release toxic gases.
A balance biomass of submerged vegetation and algae is required for
ecosystem of composite fish culture but excessive infestation is
Control of aquatic weeds
Generally the method is selected based on the dimension of the weed
infestation, size of the pond and time available.
1. Physical- manual or mechanical, various tools such as sickle, blades,
wire mess, hooks, wooden sticks, weed cutter etc. are used.
2. Biological- stocking of weed-eating fishes like grass carp, common
carp, gourami and silver barb is an effective method for long term
control and maintenance of weed population especially in grow-out.
3. Chemical or weedicides- Marginal & emergent weeds by spraying
glyphosate@3 kg/ha, foliar spray of 2-4D @ 7-10 kg/ha, phytoplankton
bloom by algicide Somazine or Diuron at 0.3 to 0.5 ppm. Anhydrous
ammonia @ 20ppm N is also effective not only in controlling the
submerged weeds but also helps to eradicate weed & predatory fish.
Strategies for development
Culture of shell fishes of India
Giant river prawn (Macrobrachium rosenbergii)
It is the largest among freshwater prawn, found in all rivers of east and
west coast of India and coastal areas throughout Bay of Bengal. It
has long sword shaped rostrum with equal no. of teeth on both upper
and lower edges. It is benthophagic omnivorous. It migrates to
estuary during breeding season.
Monsoon river prawn (Macrobrachium malcolmsonii)
It is found in all peninsular rivers of India. The second cheilipedes of
female are much longer and stouter than the body. It also migrates to
estuary during breeding season.
Macrobrachium rosenbergii Macrobrachium malcolmsonii
Water Quality Management in Aquaculture
Basic requirement of fish culture, offers favourable environment for
growth, respires with DO and get food suspended in water.
Fish Culture is influenced by various physical, chemical & biological
properties of water.
Temperature- fish can perceive a small change less than 0.10
thrive well in 18-380
C. Max. temp. in afternoon and min. in morning.
Higher temp. reduces the DO level.
pH- Indirect measurement of hydrogen ion concentration in water, less
than 4 only CO2 is absent between 7 to 10 only bicarbonate are
present , and at 11 only carbonates are present, fish die at pH 11,
diurnal fluctuation is because of CO2 conc. Used in photosynthesis.
DO- Most imp. For survival of fish, gill is the site for exchange of oxygen,
reduction in DO reduces metabolism & restricts development &
growth, sources are photosynthesis & dissolution from atmosphere,
opt. 5-12ppm, loss of DO because of respiration, decomposition,
mineralization of organic matter and direct loss to atmosphere. DO
can be improved by adding water, recirculation, use of aerators,
KMnO , and beating water surface by sticks.
I) Traditional method
Common method of fish culture
Water is maintained in an enclosed area by artificial
construction of dike/bund.
Ponds are very small and shallow bodies of quiet standing
waters with slight wind action.
Pond Preparation – There are various aspects in ponds preparation which
should be carried out before pond is used for culture for first time &
for subsequent crops. The main objective of pond preparation are to
provide fish with a clean pond base & appropriate stable water
1. Cleaning – During fish production cycle considerable quantity of
organic waste accumulates in pond bottom depending upon the
cultural practices followed. Its waste must be removed to ensure
sustain fish production from the pond. There are two methods –
a. Dry method – In this method, after the final harvest the pond bottom
is dried and crack developed primarily to oxidize the organic
components, left over in the pond after the previous culture. The
pond bottom should be dried for at least 7-10 days & the soil should
crack to a depth of 2.5 – 5.0 cm. After drying the pond bottom is
ploughed up to a depth of 15 cm.
b. Wet method – In this method, after the final harvest, the accumulated
organic matter at pond bottom is flushed out in form of a thin slurry
using a heavy duty pump.
2. Liming – Advantages
a. It corrects acidity of water.
b. It helps to raise bicarbonate content.
c. It supplies Ca, for growth of freshwater flora, molluscs,
d. It helps to establish pH buffer system.
e. It utilizes the action of Sodium (Na+
) & Magnesium (Mg2+
) ions, due
to toxic and caustic property, it helps to kill harmful bacteria.
The main objective of adding fertilizers in fish pond is to maintain the
sustain production of natural fish food organisms during the entire
1. Organic fertilizers
2. Inorganic fertilizers
• Plant and animal materials
– zooplankton feed on organic or the
bacteria/protozoa feeding on organic
• Long-term application
• Selection criteria
– low carbon : nitrogen ratio
– fine particle size
– readily available and economical
• Limiting factor in freshwater systems is often
– in late summer, nitrogen may be limiting
• Fast acting
• Selection criteria
– adequate phosphorus and nitrogen
– economical and ease of application
• Chemical designation N:P:K
• Sample prior to stocking and every week
– zooplankton net
– tube sampler
• Desirable number -> 500+ animals/gallon
2. In organic Fertilizers – These are simple inorganic compounds which
primarily contain at least one or more elements of NPK. Commercial
inorganic fertilizers used for pond culture are the same as those of
agricultural crops. Due to their high solubility in water the nutrients
become readily available soon after their application.
According to composition chemical fertilizers are –
a. Nitrogen fertilizers
b. Phosphorus fertilizers
c. Potash fertilizers
a. Nitrogen fertilizers – They contain nitrogen and are available as
ammonium sulphate, ammonium nitrate and urea. The form of
nitrogenous fertilizers are selected on the basis of acidity and
alkalinity of pond soil. Nitrogenous fertilizers are particularly
essential for newly constructed pond ( because organic matter is not
present in pond bottom). The efficiency of N fertilizers is inhibited by
It is best to maintain the P:N ratio as 1:4
b. Phosphorus fertilizers – Almost all fish ponds have phosphorus
deficiency. Phosphatic fertilizers are most effective & favourable for
- Superphosphate are most suitable in water, di-calcium phosphate is
partially soluble in water, rock phosphate is almost insoluble in
water, single super phosphate (SSP) is extensively used and easily
available, generally phosphatic fertilizers are held in soil and its
action is extended to subsequent years of its application.
c. Potash fertilizers – Potassium remain available in required quantity in
natural water. It is commonly available in form of Muret of Potash
(K2CO3) & Sulphate of Potash (K2SO4).
The favourable action of Potassium fertilizers can be seen in ponds
with low alkalinity. In general for ponds in which phytoplankton
production is rather slow, this fertilizers may be applied. It also
improves the hygienic condition of pond.
Advantages of applying inorganic fertilizers
1. Exact composition of inorganic fertilizers is advantageous.
2. Mineralization is very fast, giving quick effect on pond productivity.
3. Lack of pollution.
4. No BOD (Biological Oxygen Demand) is required for chemical fertilizers
or in other words there beneficial effect on oxygen content.
5. Used in small quantity and applied as additive manures. Hence
convenient for utilization.
Nutrient profile of some common manures & fertilizers
Sl. No. Manures/fertilizers N % P % K %
Manures of animal origin
1. Raw cow dung (RCD) 0.6 0.16 0.45
2. Pig Dung (PD) 0.6 0.45 0.50
3. Duck droppings 1 1.4 0.62
4. Poultry excreta 1.6 1.5 - 2 0.8
Manures of plant origin
1. Mustard oil cake 4.5 2.0 1.0
2. Ground nut) 7.8 1.5 1.3
3. Mahua oil cake 2.5 0.8 1.8
1. Urea 43-46
2. Ammonium nitrate 20.5
1. Single Super Phosphate(SSP) 16-20
2. Triple Super Phosphate (TSP) 40-45
1. Muret of Potash 48-62
2. Sulphate of Potash 47-50
• Fertilization in fish pond starts 10-15 days prior to seed stocking
depends upon the nutrient status & chemical environment of pond
• Proper analysis of soil & water is essential before deciding
Nutrient status of different types of soil pond
(mg/100g of soil)
P2O5 (mg/100g of
High 6.6 - 7.5 50 6 - 12 1.5
Medium 5.5 - 6.5 25-49 3 - 5 0.5 – 1.4
Low Below 5.5 Less than 25 Less than 3 Less than 0.5
Amount of fertilizers @Kg/ha/year
High Medium Low
Raw cow dung 5000-8000 8000-10000 10000-25000
Urea 112-155 156-225 226-260
Ammonium Sulphate 225-330 - -
Calcium Ammonium Nitrate - 350-500 501-650
Single Super Phosphate 150-219 220-315 316-405
Triple Super Phosphate 54-75 76-110 111-145
Quantity (Kg/ha) Periodicity of application
Raw cow dung (RCD) 2000 Initial
Urea (6.5-7.5) 25 Monthly
Ammonium Sulphate (>7.5) 30 Monthly
Cal. Ammonium Nitrate (5.5-6.5) 30 Monthly
Single Super Phosphate (SSP) 20 Monthly
Triple Super Phosphate (TSP) 8 Monthly
Aquatic insects and their control
Aquatic insects constituted about 4% of total insect fauna, which exist in the
world. Aquatic insects either in their adult or larval stage prey directly on carp
spawn or injured the young ones by sucking body fluid or indirectly competing
for food with carp spawn. Therefore, the pond culture technique includes the
control & removal of harmful aquatic insects. Such eradication of harmful
insects from ponds play a very important role in increasing fry survival rate.
However, common insects found in the culturable ponds being smaller in sizes, can
not make any harm to rather bigger sized fish including fingerlings & yearlings.
Thus removal or control of insects in stocking pond is not compulsory. Out of
11 orders of Class Insecta - 3 orders 1) Hemiptera 2) Coleoptera 3) Odonata
are relatively common in freshwater ponds.
The important families with examples under different orders are -
1. Notonectidae a. Notonecta (water boatman or backswimmers)
2. Belostomidae a) Belastoma (Giant water bug)
3. Nepidae a) Nepa (Water scorpion)
b) Ranatra (Water stick insect)
Order - Coleoptera
The important families with examples under different orders are -
1. Dytiscidae a. Cybister (Diving beetle)
2. Hydrophilidae a) Hydrophilus (Scavenger beetle)
b) Sternolophus (Water scavenger)
3. Gyrinidae a) Gyrinus
b) Dineutes (Whirling beetles)
Order – Odonata Dragon fly nymph
Order – Hemiptera
Includes water bugs, are relatively more dangerous as their complete aquatic
life both larval as well as adult stage. They have very strong piercing type
Intensity of predation
• Cybister consumes about 15-20 fry of 20-40 mm in 24 hours.
• Anisopes & Ranatra consumes 182 and 122 carp spawn respectively in 24
• Dragon fly nymph consumes about 7 fry in 3 hours & 24 spawn in 24 hours.
• These bugs secrete toxic salivary substances which kill the prey.
• Sternolophus & Gyrinus suck body fluid and even sometime kill spawn and
• Simple way of controlling is by netting but complete removal is not possible
• Application of Oil Soap emulsion in ratio of (56:18)/ha (56 L oil & 18 Kg Soap
per ha) is an age old practice. It is recommended to apply 12-24 hours before
releasing the spawn. The oil film float over the surface of water.
Mode of action of soap-oil emulsion
These insects periodically come to surface regularly for breathing atmospheric
oxygen by raising their tracheal tubes over water surface. Oil films enter into
•Least managed form of farming system
•Large ponds ranging 1 to 5 ha in area are used for
•No supplemental feeding or fertilization is provided
•Harvest – 500 to 2000 kgs /ha
II) Extensive fish farming system
Growth is limited by available food (zooplankton
feeding on pelagic algae or benthic animals, such
as crustaceans and mollusks).
Tilapia filter feed directly on phytoplankton, which
makes higher production possible.
III) Semi-intensive fish farming
– Involves rather small ponds (0.5 to 1 hectare in area)
– Natural food developed by fertilization and with or
without supplemental feeding for fish but in shrimp
supplement feeding is done
– Harvest – 2500 to 10000 kgs (Fish) and 1500 to 2500 kgs
Intensive fish farming system is the well-managed
form of fish farming
To achieve maximum production of fish from a
minimum quantity of water
This system involves small ponds/tanks/raceways
with very high stocking density (10-50 fish/m3
IV) Intensive fish farming system
• FLOW THROUGH METHOD (Raceway
• Raceway culture is defined as raising of fish in
running water. Raceways are designed to
provide a flow-through system to enable
rearing of much denser population of fishes .
• Source of water: springs, streams, deep wells,
• These are much smaller and occupy less space than
• Made up of concrete or cement blocks or may be lined
by plastic material.
• Raceway farms can have Series/Linear design or
Parallel/Lateral design series.
• Slope: 1-2 %
• One segment: 30 m Long, 2.5-3.0 m wide at bottom and
1.0-1.2 m deep.
• Contains 10-20 segments.
• All segments should be straight to ensure uniform flow.
Linear type/Series design: Ponds arranged in sequence the
volume of water entering each pond is larger and as the same
water is used repeatedly from pond to pond, occurrence of
disease in initial ponds may directly affect the other
Lateral type: Ponds laid out in parallel in this type the
volume of water entering each pond is smaller but a fresh
supply of water is always ensured, and no transfer of disease
from one pond to another.
• The main benefit of RAS is the ability to
reduce the need for fresh, clean water while
still maintaining a healthy environment for
Recirculating Aquaculture system (RAS)
A Recirculating Aquaculture System (RAS) can be
defined as an aquaculture system that incorporates
the treatment and reuse of water with less than 10%
of total water volume replaced per day.
Solids are flushed out or vacuumed out manually using a siphon
. Dissolved oxygen levels can be increased through two methods
aeration and oxygenation. In aeration air is pumped through an
air stone or similar device that creates small bubbles
pH is controlled by :
•addition of lime (CaCO3) or sodium hydroxide (NaOH).
•degassing CO2 in a packed column or with an aerator
↓ pH leads to ↑ CO2
• Reduced water requirements as compared to
raceway or pond aquaculture systems.
• Reduced land needs due to the high stocking
• Site selection flexibility and independence from a
large, clean water source.
• Reduction in wastewater effluent volume.
• Ability to closely monitor and control
environmental conditions to maximize production
efficiency. Similarly, independence from weather
and variable environmental conditions
• High upfront investment in materials and
• High operating costs mostly due to electricity,
and system maintenance.
• A need for highly trained staff to monitor and
operate the system.