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Shrimp Toilet: A novel way for disposal of organic waste in Aquaculture

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Article · September 2018

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Md. Idrish Raja Khan

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 ARTICLE Shrimp Toilet: A novel…

Shrimp Toilet: A novel way for disposal of organic

waste in Aquaculture systems
Md. Idrish Raja Khan

INTRODUCTION an excellent example where improper handling of organic

Global aquaculture production doubled during the last decade, waste material may lead to a catastrophic result. The excess
making it one of the fastest growing food production sectors feed and the fecal matter released by aquatic organisms
in the world. According to the FAO, aquaculture provides ultimately reaches to the center of the pond where most
47% (51 million tons) of the global human fish consumption. anaerobic conditions exist leading to the formation of
In order to keep up with population growth and increasing ammonia and hydrogen sulphide simultaneously leading to
per capita fish consumption, aquaculture output is set to the stress on the animal. This stress gives chance to many
increase by a further 60–100% over the next 20–30 years. As opportunistic pathogens for early and easy infection. To avoid
to achieve the greater level of production the aquaculture this kind of problems farmers in South-east Asian countries,
systems are now intensified and ponds are the most Bangladesh and in India especially in Andhra Pradesh and
commonly used aquaculture production system accounting West Bengal, are showing interest in establishing shrimp pits
for about 40% of the world production. A vast majority of the or shrimp toilets or central drain at the center of the culture
farmed freshwater fishes and nearly all farmed crustaceans pond. For this purpose, they are utilizing about 5- 7% of the
are cultured in ponds as super-intensive or intensive or semi- total surface area of pond. Ideally, the pond size should be
intensive aquaculture systems. Intensification of ponds about 1000-5000 m2 for the establishment of shrimp toilet.
Establishments include 7-10 feet concrete cement with a
allows accumulation of organic matter during the culture
smooth slope to the center where there will be a small well
cycle due to the administration of high levels of external
of about 2-3 feet depth. Smooth and slope surface (25-30o)
inputs (mainly formulated feed and fertilizers). The organic
at center allows fast movement of waste toward the central
waste material (excretory products) from the target culture
pit with the additional advantage of lesser requirement of
organisms is also a considerable source of lodging of
water with concentrated organic waste removal. By the
organic debris. Uneaten feed and feed derived metabolites
continuous movement of water by intensive aeration all the
accumulate in the sediment where they are decomposed
waste materials will be dragged in to well. This waste can be
under aerobic or anaerobic conditions. But excess lodging
removed using a siphoning motor or submersible or floating
leads to malfunctioning of the decomposition cycle in the
pump (power of about 2 hp) for every week so that there
pond bottom. Aquaculture ponds are dynamic and complex
will not be any sludge. Natural gravitational force can also be
ecosystems, which will only produce the targeted cultivable
used for draining the organic waste like in central drain.
production if nutrient cycling and waste decomposition are
properly managed. In the recent time, there is an addition to shrimp toilet
concept is an HDPE and rubber parabola cover (2.5 meters
A number of physical, chemical and biological methods used
in diameter), placed over the central drain of a pond. The
in treating this kind of problem, management practices
purpose of the keeping parabola is to extend the area of
influencing the load and decomposition rates in ponds include
sludge removal. They were kept about 2-3 feet above the
water exchange, sediment pond bottom which allows
removal, aeration, fallowing
period between crop cycles,
Highlight Points creation an extra suction
force and also preventing
liming etc. In recent time
there is a noble concept of • Intensification of aquaculture systems brings some unnecessary losses of
target organism through the
shrimp toilet or central drain problems like accumulation of organic wastes within
central drain. Establishment
applied by aquaculturists the systems of a parabola in the pond may
SHRIMP TOILETS • Organic wastes invites the various infectious and non- lead to limited use of manual
The sludge formation at the siphoning.
infectious diseases
pond bottom is the prime Scientifically, about 500 gm
cause of the evolution of many • Shrimp toilet seems as an alternate option as cheap, of organic waste is produced
infections in shrimp farming. eco-friendly and sustainable option to overcome the in the production of 1 kg of
The recent occurrences of loading of waste material problems. shrimp. For the production
severe diseases and downfall target of 7 tonnes/ hac
in aquaculture production are with the stocking density
52 • AQUA INTERNATIONAL • September 2018
AI SEPTEMBER 2018 issue.indd 52 29/08/18 6:55:44 PM
 ARTICLE Shrimp Toilet: A novel…
of 30 pieces/ m2 farmers can accumulate a minimum of
3.5 tonnes of sludge which must be disposed off in an eco-
friendly manner. The concentrated sludge if released into
the nature untreated has the capability to trigger pathogen
which could cause mass mortality in short period of time.
Concentrated sludge should not be released directly into the
natural resources and instead allowed to settled, treated and
then be disposed. The farmer should demarcate 5% of the
total culture area as a sludge pit to accumulate the sludge
while farming and then dispose it to a safer area after the
completion of the culture phase. There should also be a
proper design for the pit to facilitate an eco-friendly way for

Working principle of shrimp toilet

Aquaculture pond with intensive aeration

(circular movement)

Working principle of central drain

Dried pond with cental drain at bottom

HDPE parabola
Advantages of shrimp pits:
1. Reduces the chance of infections/ infestation- Early
mortality syndrome (EMS) or Acute Hepatopancreatic
Necrosis Disease (AHPND), Enterocytozoon Hepatopenaei
(EHP), White Fecal Disease (WFD), White Muscle Disease
(WMD) etc.
2. Animals will be stress-free
Central pit of shrimp toilet 3. Avoids usage of chemical at high doses
the sludge disposal. Moreover, properly treated sludge could 4. Ammonia and Hydrogen sulphide formation will be very
also be used as organic manure for agriculture. This would less
be beneficial to the agricultural farmers for their farmlands in 5. Controlled/ Improved FCR
the surrounding areas. 6. Pollution free aquatic environment etc
54 • AQUA INTERNATIONAL • September 2018
AI SEPTEMBER 2018 issue.indd
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