video was filmed by the author during a visit to the Sea World, California,
shown in the video, visitors surrounding the touch tank are trying and actually
touching the stingrays which is a unique experience.
order to ensure a safe touch, the barbs (stingers) of rays are constantly trimmed
down like trimming fingernails, so the de-barbed stingrays are safe to interact
with and touch.
According to large aquariums, the trimming process is done every three
months whereas each ray is gently taken out of the water to trim the barbs for about
Photo credit: Sabi Asma (Togo) Description: Sabi Asma and Abdel Rahman El Gamal (Founder of the website)
inserted pictures show one of the aquaponics projects in Togo. This one is a
private farm located in Plateau Region, prefectures of Kpele, and locality of
Bodze. This particular farm was established in 2012.
fish component in this project is represented by Nile tilapia (Oreochromis
niloticus) and African catfish (Clarias gariepinus). The plant component is
almost the typical aquaponics plants such as spinach, lettuce and others.
This project relies on
I delivered this presentation in an online workshop held on 27 July 2020. The management of the workshop took place at the Egyptian International Centre for Agriculture (EICA), Dokki, Egypt. The structure of the workshop included three main presentations (this is one of the three) as well as presentations from selected African countries. By the end of the 4-hour event, there was a question and answer session. This workshop has been sponsored by EICA in partnership with the Japan International Cooperation Agency (JICA).
About a month prior to the workshop, a questionnaire was developed by the author and circulated by EICA among selected African aquaculture specialists. The analysis of the feedback has been done by the author as presented in this document.
Photo credit: Samy Ndala (Congo DR) Review: Abdel Rahman El Gamal (Founder of the website)
The supersaturation of dissolved
oxygen (DO) is often observed near the surface of water bodies as a result of
the strong the photosynthetic activity resulting from phytoplankton abundance.
This occurs during bright sunlit days in eutrophic water bodies such as rivers,
lakes and/or fish ponds. The supersaturation of oxygen during daylight is always
followed by much lower oxygen levels at night when the photosynthesis ceases
while the respiration by all living organisms continues.
For illustration, the dissolved oxygen in the inserted photo
reads 14.8 mg/l which is much higher that the saturation levels of dissolved
oxygen. For example, the 100% DO saturation is 8.09 mg/l at water temperature
of 26°C and 7.81 mg/l at 26°C. This photo was taken during
August in a freshwater fish pond in Egypt where temperature is usually at
highest and so the sun light. One can notice the dark green color of pond water
indicating the abundance of phytoplankton in the water.
worth mentioning that in highly productive fish ponds,
some DO may be lost to the atmosphere through oxygen supersaturated surface
Review: Abdel Rahman El Gamal (Founder of the
Lotus-aquaculture culture system
has been practiced for long time in China and is being evaluated recently in
some Asian countries where lotus (Nelumbo
nucifera) is native macrophytes. Several fish
species have been used in such integrated systems including carps, tilapias and
The two culture forms are either
the co-culturing of two crops in the same field and for the same time or apply
the rotation type in which the culture of each crop is done individually in a
one after another pattern.
The evaluation of lotus-aquaculture
systems has always considered the technical as well as the economics of such
integrated systems. Even the outcomes of the two forms varied and could be
related to the culture conditions, there have been some agreements. For
example, in the co-culture form, the shading resulting from the shading of
lotus leaves which reduce the phytoplankton production and hence the dissolved
oxygen in the water. Added to that, if the dead water leaves were not removed
from the pond, they decompose and worsen the dissolved oxygen situation which
is not in favor of fish production.
Regarding the lotus, fish can feed
on aquatic grasses that may compete with lotus for living resources. Also, fish
excreta would be a good source of organic fertilizers that leads to enhanced
lotus growth. Feeding fish on harmful
pests is another benefit of such co-culture method.
On the rotation form of lotus-aquaculture, the main advantage is having
two different crops instead of one bigger crop. Also, the fish crop would
assist in releasing the trapped nutrients from the pond bottom to be usable in
the subsequent culture of lotus in an ideal recycling
Photo credit: Vaghih El Bechiry (Mauritania) Description: Vaghih El Bechiry and
Abdel Rahman El Gamal (Founder of the website)
The inserted picture
shows a group of fishermen while fishing in Gorgol River “Gorgol Noir” which is
an open fishery resource and hence there is no fishing license is required. In
order to achieve enough sustainability of fishery resource, the fishery
department determines the mesh size of the fishing seines to be not less than
40mm. There is ongoing stock enhancing program whereas fish fingerlings are
stocked in the river. In fact, the plan is to establish a fish hatchery in Lakleta
for supporting the stock enhancement program.
Photo credit: Nyro Tum (Cambodia) Description: Nyro Tum and Abdel Rahman El Gamal (Founder of the website)
The inserted picture shows a field day tailored to make
potential small-scale farmers acquainted with aquaculture. Field days are
typically conducted to train farmers who are already practicing fish farming
targeting to introduce enhanced technologies and/or addressing current
problems. Preparing such field days usually requires technical and financial information.
Photo credit: KIVA Review: Abdel Rahman El Gamal (Founder of the website)
Senegal, the mangrove roots and mud are home of several hundreds of known
species of fish, bivalves and oysters, and crustaceans, which are very
important especially for domestic consumption.
are the ones who are in charge of the collection of oyster from mangrove
forests as well as in the processing of collected oysters. Women have the experience
in identifying the sites that are still in good condition in regard to the
oyster density and those with low density or exhausted.
access the mangrove sites either on foot or in small rowing canoes. For oyster
harvesting, women use simple tools are simple including a spoon to dig up the
shells, a knife for the oysters, and baskets for the harvest. Upon harvesting,
women have the experience that the practice needs to preserve the resource
mainly through keeping the green (live) roots of the mangroves undamaged except
in certain conditions such as the wood is dead or when the roots are very dense
bearing in mind that the roots of mangrove trees where the oysters are found.
After harvesting, women
also process the harvested oyster. They usually have the experience to crave
the oysters out of their shells using a proper knife.
Video credit: Mohamed Atta (Egypt) Review: Abdel Rahman El Gamal (Founder of the video channel)
Vietnam has the lead in the production of striped catfish (Pangasius sp.)
that is exported to over 100 countries. According to FAO statistics, about 1.3
million tons of Pangasius has been produced from aquaculture in 2018.
The culture of Pangasius is mainly practiced in cages,
earthen ponds and to a lesser extent in pens.
The inserted video shows the feeding of Pangasius in a commercial fish pond where a small boat is used to spread the feed within the pond. The aggressive feeding is quite obvious as shown in the video. Typically, the stocking rate rages from 20-40 fish/m2, increasing to higher rates in intensive practices with a production of about 250-300 tons/ha/crop. On the average, Pangasius can reach 1.0 – 1.5 kg as an average size after 6 months which is an optimum size for the market.
Photo credit: Vaghih El Bechiry (Mauritania) Description: Vqghih El Bechiry and Abdel Rahman El Gamal (Founder of the website)
The fish display shown in the picture exists in
the central market located in Mokama city, South of Mauritania. The fish
displayed in the market are caught from Foum Laklet Lake about 80 km from
Mokama. Fish during transportation is usually iced. As normally the case, the
man shown in the photo is the fish seller while the buyer is the woman.
Fish displays are often dominated by tilapia,
followed by bayad (Bagrus bayad). During the rainy season, African catfish (Clarias
gariepinus) contribute to the fish trade in the market. In addition to the
mentioned species, other less important species may be displayed in the market.
As the case with traditional fish market, there
are wholesalers who deal directly with fishermen while retailers have their
displays and sell directly to fish buyers.
It may worth noting that the capture fish
production from Mauritania in 2017 amounted 794,580 tons while the per capita
consumption of fish was 8.2 kg/year in 2016 bearing in mind that most of
produced fish is exported (449, 835 tons in 2016).