Photos’ credit: Debora Amsi (Tanzania)Description: Debora Amsi and Abdel
Rahman El Gamal (Founder of the website)
The inserted photos are taken in a fish farm located in Dar es
Salam – Pugu Kinyamweei (Tanzania)
The farm was established in 2013. The farm has enough
numbers of nursery and grow-out ponds. In addition to fingerlings and table
fish production, fish feed is also produced (e.g. floating pellets with 30%
protein). Regarding to supporting the society, the farm provides training on
aquaculture.
Video credit: Elsadig Arbab (Sudan) – Description: Elsadig
Arbab and Abdel Rahman El Gamal (Founder of the video channel)
The inserted post (video) shows a visit
to a cage farm of tilapia in Brazil. The visit was accomplished by high level
delegates from Sudan and took place during 2014.
The cage units shown belong to a
private enterprise located in a small Amazonian river in Toledo (Sao Jose). The
operation is a complete one including units for the production of fingerlings,
feed mills, and quality control units that process the harvested tilapia from
the floating cages. The enterprise manages 1200 cages.
Cages are square in shape with 3 x 3
meters and 2.5 m depth. The strain stocked in the cages are all-male
fingerlings Thai Nile tilapia (Oreochromis niloticus) as well as GIFT
strain (Genetically Improved Farmed Tilapia). All-male fingerlings have been
produced through hormonal treatment.
In
order to produce two cycles/year, the average stocked tilapia juvenile is 60 g.
Different sizes of floating pellets are used ranging from 1 mm (37% protein) to
5 mm (28% protein)
The production averages 90 kg/m3 of marketable-size fish of 600 g as an average size.
https://youtu.be/YPsdzgp4kg0
Note: I liked very
much the design of the cages especially the simple apparatus that enable 2
persons to move the cage bottom easily
Video credit: Mohamed
Atta (Egypt) – Review: Abdel Rahman El Gamal (Founder of the video channel)
The inserted video
was filmed in a private fish hatchery in Vietnam. The video began with the egg
stripping upon the ovulation of two females. One can notice that the egg volume
varied among the two females with much more eggs in the second female compared
to the first one. The video shows the gentle pressing on the female’s body and
eggs stop free flowing, the female was considered a spent and was taken to a
recovery pond. The two batches of eggs were mixed and dry-fertilized by the
sperm directly stripped from one male. As shown in the video, a bird feather is
used for the gentle mixing of eggs with the sperm. Typically, after the
water-hardening of eggs, they will be incubated until hatching.
This introductory lecture was delivered in the
opening of the “Aquaculture training workshop” which was conducted during the
period from 07 to 12 October 2018 and held in Khartoum and hosted by the Agricultural
Bank of Sudan.
In this lecture, I tried to bring in the information
on fishery/aquaculture sector in Sudan as well as to highlight other related
sectors such as particular agricultural crops which could be used in fish feed.
In order to emphasize the rationality of aquaculture development in Sudan, the
key parameters related to human nutrition have been addressed such as the daily
per capita protein intake and identifying all sources for such intake. The
lecture ended by the challenges facing the development of aquaculture in Sudan.
A brief introduction on world and African aquaculture was included in the first
part of the lecture. As planned, this lecture served as a platform for
subsequent components of this training workshop. This workshop was
attended by 30 participants affiliated to the fishery sector in Sudan and the Agricultural
Bank of Sudan.
Photo credit: Kaulo Salushando (Namibia) – Review:
Abdel Rahman El Gamal (Founder of the website)
The inserted picture
shows the catch of African catfish (commonly known in Namibia as sharp-toothed
catfish), Clarias gariepinus. The shown specimens were caught
from the Naute Dam.
The
Naute Dam which is the third largest dam in Namibia was built between 1970 and
1972. The dam holds up to 69 million m3 of water
Dams including Naute Dam are
popular freshwater angling spots in Namibia where several fish species
including tilapia, tiger fish, and African catfish can be caught there. The
inserted stamp demonstrates the status of catfish in freshwater fishery in
Namibia.
Regarding food security, and according
to the Namibian bill on freshwater fisheries, the priority is given to food
security of local communities and hence efforts have been given towards a sustainable
development of inland fisheries to benefit local communities with more focus on
subsistence fishery above commercialization.
It
may worth noting that several Namibian reservoirs including the Naute Dam provide
habitats for water birds and hence are considered tourist resorts for angling
and water sports.
Photo credit: Marx Perfecto C. Garcia (Philippines) Description: Marx Perfecto C. Garcia and Abdel Rahman El Gamal (Founder of the website)
As established, the turbidity caused by eutrophication and
phytoplankton bloom in fish pond is a dangerous incidence that may ultimately
cause stress and even kill of stocked fish. Means for the control of the
plankton bloom varied through management practices or use of chemicals. The
inserted picture shows the application of chlorine dioxide in a fish pond in
China. In this particular application, an amount of 500-g of chlorine dioxide
powder is mixed in the boat container with about 50 to 80 L of water. The
solution is broadcasted throughout the pond areas using a boat. The solution is
sufficient for a pond area of about 3,000 to 4,000 m2.
The use of chlorine dioxide for such purpose is based on the
ability of the compound to readily dissolve in water and so its effectiveness
in the control of algae. In addition, the safety of using chlorine dioxide has
been endorsed by international organizations related to food and environmental
safety including the Environmental Protection Agency (EPA) and other organizations
as well. Interestingly, the US Food and Drug Administration (FDA) permitted the
use of chlorine dioxide as a food additive for human consumption.
While
the primary use of the chlorine dioxide is for bleaching of wood pulp, it is
also used for the bleaching of cereal flours and for the disinfection
of municipal drinking water. The product has been registered for the use as
a disinfectant and sanitiser in animal farms, food-processing and storage
plants. Its use as an antimicrobial agent has been adapted in the
water of poultry processing as well as in water used to wash fruits and
vegetables, and for rinsing food processing equipment.
A unique application of chlorine dioxide occurred in 2001, when
used to decontaminate a number of public buildings following the release of
anthrax spores in the United States.
Precaution: A
rule of thumb if any algicide is applied to a fish pond in the existence of fish, aeration should be performed to pond water to prevent the risk of fish suffocation due to the
lowering of dissolved oxygen caused by algae kill. As expected, the risk of
oxygen decline will be influenced by the dense of plankton bloom and the level
of algal kill. In situations, when the effective aeration is not possible, it
is advised to find out other means for controlling dense algae rather than
using chemical algaecide. On the other hand, in situations where
algaecides is applied prior to fish stocking, all what is needed is to monitor the
level of dissolved oxygen and fish stocking takes place once oxygen is back to
normal after algicide treatment.
Photo credit: Ariel Montiel Benitez
(Paraguay)
Review: Ariel Montiel Benitez and Abdel Rahman
El Gamal (Founder of the website)
The inserted picture shows a section of the National Fry Production Center in Paraguay where the fingerlings of Nile tilapia (Oreochromis niloticus) are produced. As shown in the inserted picture, school children and young people from Paraguayan universities are taking part in the internship.
Tilapia being not native to Paraguay, the introduction of Nile tilapia (O. niloticus) into Paraguay dates back to 1960 and was imported from Ivory Coast (Côte d’Ivoire), by a French technical mission. Later on, in 1990, the Fisheries and Aquaculture Department of the Faculty of Veterinarian Sciences (National University) introduced improved Nile tilapia (O. niloticus). According to FAO, the total aquaculture production in Paraguay, amounted 8500 tons in 2016. Out of which Nile tilapia is commercialized alive, fresh, frozen, and/or filleted.
Review: Abdel Rahman El Gamal (Founder of the website)
A Passive Integrated Transponders “PIT” tag is biologically inert small glass-encapsulated electronic microchip with a standard length that ranges between 10 and 14 millimeters and about 2 millimeters in diameter. Because the PIT is inert and has no internal battery, it remains dormant until its circuitry is activated by a close-range, electromagnetic field generated by the reader (scanner) where the unique alphanumeric code is received from the tag and displayed on the scanner. The PIT is injected and pushed in the body cavity of tagged fish. Because the PIT tags can last through the life cycle of tagged fish, its use is justified in breeding programs. The tagged fingerlings as shown in the video are anesthetized. As shown in the video, potassium permanganate has been used to disinfect the needle and to clean the wound.
Video credit: Charles Bernard Makuya Description: Abdel Rahman El Gamal (Founder of the video channel)
Because of
the superiority of tilapia males over females in regard to growth rate, several
scenarios are adopted towards the culture of all-male tilapia. Whether the use
of male hormone (17-alpha methyl testosterone) is permitted or banned, its use
is widely practiced in the sex reversal process.
In order for the hormonal treatment
to be highly effective, the treated fry should be at a very young age and hence
the hormonal treatment covers the period of sexual un-differentiation that
lasts 22 days for tilapia ending by all-male tilapia seeds that are targeted
for the use in farming operations.
While controlled reproduction through
the collection and incubation of fertilized eggs allows knowing the age of
hatched fry, and so the hormonal treatment is applied to known age of tilapia
fry and so, if all elements of the sex reversal process are properly applied, a
very high ratio of produced males is expected.
In regard to the mass spawning that depends on
the collection of fry, the age of fry cannot guarantee to be the optimum.
Instead, the size of fry is used to indicate its age. Based on the scientific
findings, the fry with a total length of 11-12 mm are suitable for the
sex-reversal process. On the other hand, the effectiveness of the hormonal
treatment on larger sizes produces questionable results. In order to have the
optimum results of the grading of collected tilapia fry, a grader with a 2.5 mm
opening (mesh) is recommended; the passed fry undergoes the hormonal treatment while
retained fry could be used in different farming systems.
Photos’ credit: Hassan Shettima Modu (Nigeria) Description: Hassan Shettima Modu and Abdel Rahman El Gamal (Founder of the website)
The photos show a type of fish smokers used to produced tilapia and African catfish. The consumer preference for smoked fish is high due to its taste, color and texture.
The smoker shown in the pictures is made of aluminum with insulator sheet. The bottom pot is used for loading the charcoals required for the smoking process. The smoker compromises of five to seven trays depending on its size. The capacity of shown smoker is about 50 kg of fish. Typically, a period of seven to eight hours is produced high quality smoked product.
