Page 14 - FULL YEAR BOOK 2021

Editorial

world are aimed at fresh water species
such as salmon, tilapia, catfish etc. Devel-
opment of systems for marine species is
still lagging behind.
‘One size does not fit all!’ – Different
species, even within the same tempera-
ture range may need different designs
to deal with various issues such as in-
creased CO2, increased ammonia, stress
etc. One of the reasons for RAS projects
failures is the use of a ‘standard’ design
and the expectation of having similar
output from a system based on results
from different species.
Recirculating Aquaculture Systems
can be designed as a complete closed
(or almost closed) system with minimal
top-up water or a simple system adopt-
ing just a few of the RAS components.
RAS can be designed and built from
the ground up or retrofitted to an exist-
ing system.

For example, in South East Asia, the
ornamental fish industry in many cases
comprises of small, ‘back-yard’ systems
South East Asia) shrimp are now raised • Necessity for oxygen supply 24/7 (in made of small concrete tanks with static
in RAS facilities. CPF hope to raise ALL high biomass) or very low flow of water. A simple ap-
its Thai shrimp in bio-secure, resource- • In case of pathogen infection, the paratus comprising of an integrated bio-
efficient RAS farms by 2023. whole system must be emptied and filter can reduce the ammonia in the tank
RAS offers many benefits to the disinfected and increase water quality. Such biofil-
ters can be made locally from simple
aquaculture industry: • Very short response time in case of materials and have significant impacts
• Fully controlled environment for the technical/human failures on fish growth and survival.
fish and shrimps Due to these constraints, the adapta-
• Low water use coupled with high tion and development of RAS is still slow. Small and compact RAS can be suit-
quality water Moreover, while commercial companies able to the Middle East / Arabian Gulf re-
• Efficient energy use offer RAS for almost any cultured spe- gion, offering a small footprint and ease
• Efficient land use cies, most of the RAS projects around the of use. Such systems can offer an easy in-
• High density culture
• Healthier and stronger fish
• Minimizes volume of effluent,
facilitating waste recovery
• Allows for increased control over the
culture environment
• Improved biosecurity and disease
control
• Environmentally sustainable
However, there are some constraints
with RAS:
• High upfront investment in materials
and infrastructure
• High operating costs
• A need for highly trained staff to
monitor and operate the system
• Necessity for electricity 24/7

12 Arab Agriculture 2021

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