International Journal of Aquaculture, 2018, Vol.8, No.12, 90-97
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the possibility of effective management. More than 5 tonnes/ha/yr fish production is achieved from the average
pond size of 0.6 to 1 ha (Biswas et al., 2018).
2.1.1 Aquatic weed and weed fish control
Aquatic weeds hamper primary productivity and soil hinder normal penetration of sun light and wind action and
upsetting the oxygen balance, creating obstruction in movement of fishes and in netting operations etc. Removal
of weeds is done by manual or mechanical, chemical or biological means (ICAR, 2014). According to Hussain
(2012), the mechanical or manual method is preferable due to no side effect. Removal of unwanted and predatory
fishes and other animals is done by repeated netting or using mahua oil cake (produced from
Bassia latifolia
) @
2,500 kg/ha/m water depth or by sun drying the pond bed. Biswas et al. (2017) have found different in 24 Pgs. (N)
district, West Bengal that 87% of the farmers use 3,200 kg/ha mahua oil cake as fish toxicant and aquatic insects
are eradicated through both repeated netting.
Weed fishes (e.g.
Puntius
sp.,
Oxygaster
sp.,
Ambassis
sp.,
Amblypharyngodon mola
,
Colisa
sp.,
Rasbora
sp., etc.)
are those which compete with the culturable species of fishes for food, space and oxygen and causing serious
problem to fish culture (Sinha et al., 1985). According to Rath (1993), removal of unwanted fish through physical
methods like dewatering and de-silting of ponds, repeated netting operations, hooks and lines with baits are found
to be incomplete and uneconomical. Biswas et al. (2017) have expressed that in practical field farmers use
pesticides viz. Nuvan (Dichlorvos or 2, 2-dichlorovinyl dimethyl phosphate), Ustaad (Cypermethrin) etc.
2.1.2 Liming
Soil and water management is an essential step for optimising fish production (Sinha et al., 1985). Application of
lime is done not only for fertilizing the pond but also as a remedial measure necessary in acidic pond. Lime
application has many benefits in culture pond system viz. (i) neutralization of acidity (ii) increase in pH of bottom
soil and thereby enhancing the availability of phosphorus added in fertilizer, (iii) accelerating the microbial
activity and thereby diminishing the accumulation of organic matter in pond bottoms and favouring recycling of
nutrients, (iv) maintaining the alkalinity and other physico-chemical characteristics of soil which in turn helps in
enhancing fish/shrimp production, and, (v) improving the hygienic condition of pond bottom (Hussain et al.,
2011). The normal doses of the lime desired ranges from 200 to 250 kg/ha. However, the actual dose has to be
calculated based on pH of the soil and water (ICAR, 2014).
2.1.3 Fertilization and manuring
Fertilization keeps the metabolic cycle in operation, increases natural productivity (Huet, 1986) and as a means of
increasing fish production is well accepted (Chakrabarty et al., 1975). Fertilizers are broadly two types: organic
and inorganic. Organic fertilizers are of plant origin and inorganic fertilizers are of mineral origin. Animal wastes
are important resources that are used to supplement organic matters and improve soil conditions (Garg and
Kaushik, 2005). According to ICAR (2014), farm yard manure; cow dung @ 5,000 kg/ha and poultry or sheep
manure are optimum for better fish production in composite fish farming. According to Biswas et al. (2017)
before stocking, cow dung @ 10,000-11,000 kg/ha was considered better towards fish production. Parvez et al.
(2006) reported that
C. mrigala
and
C. carpio
respond best in manured ponds with homestead organic wastes
while
C. idella
do not show any marked response.
2.2 Stock management
2.2.1 Species composition
Selection of species plays an important role for any culture practices. In India, suitable and most common
combinations of fish for composite fish culture system used to be are catla, rohu, and mrigal along with grass carp,
silver carp and common carp (Rahman et al., 2006). However, other minor fishes viz.
Ompok bimaculatus
,
Mystus
seenghala
,
Notopterus chitala
,
Pangasius pangasius
(Chaudhuri et al., 1974),
Mugil cephalus
(grey mullet) and
Macrobrachium malcolmsonii
,
M. rosenbergii
(giant freshwater prawns),
Channa marulius
(Govind et al., 1976)
and
Clarias batrachus
(Tripathi, 1981) have also been experimented with in sizable numbers in composite fish
culture (Hussain et al., 2013).
