Asmak Articles
Crayfish
Crayfish is a Procambarus Clarkii the most common type of cambaridae family that is spread widely and represents 90% of the yearly yield of this kind of crustaceans in Louisiana, United States of America. This type has been spread recently in Egypt with such intensity and fast all along the banks of the Nile.
Procambarus Clarkii is one of the most important food source for it contains a high amount of protein, the stomach muscles itself contains 10 – 40 % of weight from the regular body weight. It is also used as bait in fishing and as a sample of Arthropods dissection in the universities laboratories.
Crayfish is considered a cheap resource of animal protein for human and its biological role in controlling the Schistosomiasis snails and sea weeds. It also plays an essential role in improving water quality. Crayfish is propagated quickly; its wastes can be used in
fish diets after drying and grinding it.
Types of marine fish cages:-
1- Square cages.
2- Circular cages.
3- Open sea cages.
4- High sea cages.
5- Ocean spare cages.
Cages and net pens are culture chambers that are designed for use in locations that are not suitable for pond construction or rearing animals in raceway systems. Net pens are used almost exclusively in the marine environment, while cages have been used in both salt - and freshwater culture operations.
Ornamental fish culture
Types of aquarium
There are three main types of aquariums to choose from
1-All glass tank made from five panes to glass bonded together with
Silicon-rubber adhesive. .
2- One piece , plastic tanks .
3-Angle-iron forms with glass panels inset with putty.
The main aim should be something that fished can live in comfortably,
And that will remain functioning with a minimum of maintain one an
Aquarium makes good use of a corner of house .
The overall water capacity of aquarium is not the most important
Contributing factor to the aquarium caring capacity .
Much more important than size is the shape or proportion of the aquarium .
In term of numbers of fishes that may be stocked in any part culture
Size aquarium .
Considertion must be given to the final sizes that the fishes will reach
In the aquarium , fish bought from dealer are usually fries and can be
Expect to be double in size at least .
Difficulties of aquaculture and improvement methods
We all know that every one needs food of different sources of protein. The main method to have protein is represented in animal protein which found in meat but we faced some new problems which are shortage of this kind of protein so, fish production is the best way to decrease this gab of animal protein and to recover the shortage of red meat. There are many reasons direct us to increase the interest of fish production in Egypt because the water resources is twofold of agriculture lands and we own a huge resources that could be used in enhancement of fish production.
Fish Smoking
Smoked fish is prepared from fish that has undergone a hot or cold smoking process that
renders a product that is generally eaten without further cooking. The smoke must be applied
through a traditional smoking process and the end product must have smoked sensory characteristics.
Smoking is the traditional process of treating fish by exposing it to the smoke from burning or
smoldering plant materials [or smoke concentrates (liquid smoke) derived from burning or
smoldering plant materials]. The traditional process is characterized by an integrated
combination of salting, drying, heating and smoking steps in a smoking chamber (kiln).
The characteristic golden color of the smoked products is due to the interaction of
carbonyls with amino components on the flesh surface. Flavor is the most typical feature of
smoked products. It is generally considered that phenol compounds and other components soluble
in water are the most important factors imparting acceptable flavor in smoked products.
Smoking methods
Fish preparation for smoking
1- Washing
2- Salting (with different methods)
• Dry salting
• Brine salting
• Mixed salting
3- Desalting
4- Partial drying
5- Smoking: there are different methods for fish smoking such as:
• Hot smoking is a smoking process in which pre-salted and pre-dried fish is
smoked at an appropriate combination of temperature (70-80°C) and time (2-3 hours)
sufficient to cause the complete denaturation of the fish flesh, to kill parasites
being present completely and to destruct non-spore forming pathogens of human concern.
• Cold smoking is a smoking process in which fish is treated at an appropriate temperature
(25-30°C) and time combination sufficient to lower water activity (drying). A cold
smoking process will not cause considerable coagulation of the fish flesh.
• Electrostatic smoking
• Smoking by liquid smoke
Sea bream care and nutrition
Water types is identified by the degree and rate of salinity as follows:
Fresh water Brakishwate - saline water more salyy water.
Technical and economic aspects related to different types of marine fish.
- Sea bream ( Sparus auratus ).
- Sea bass ( Dicentrachus Labrax ).
- Mullet fish.
These are the common marine fish culture in Egypt sea bream a
re able to adjust their diet in take in accordance with their nutritional needs.
Trade and marketing of Tilapia fish in Egypt
Tilapia fish is pharaoh in origin however it spread all over the world and became very common because
of its characteristics, for it is easy, propagated quickly,
multiple in its food, and its high resistance of environmental changes and diseases.
The international expansion of producing Tilapia led it to rank high position, more than 2.5 million ton in 2006,
Egypt comes in the second position after China in producing Tilapia, the fish prices went high in May 2008 and reached
to 9 – 11 L.E and in 2009 it went to 13 – 15 L.E for the kilo. And this happened because of the spread of diseases in Fish farms,
the high prices of its food and the growing demand on all fish products whether it is frozen or fresh.
Quality fish food and HCCP
Hazard analysis and critical control point (HACCP)is a preventive management system that can be used to anticipate and control hazards at aquaculture operations and processing based on seven basic principles, HACCP.Plans identify critical control points and critical limits, and establish monitoring methods, record- keeping procedures and appropriate corrective actions. Verification provides confidence that plans are based on sound Scientific principle, and are controlling hazards. Meanwhile there is a new program will be applies in aquaculture after have a license from FDA (Food and Drug Administration) called BAP (Best Aquaculture Practices Program).Inspects each component of the supply chain ,verifies the food safety of final products and traces them to the market .
New technology for fish processing
The aim of fish research in that days tend its restuts forromared to fish processing
and its production in human consumption and used in another fish processing for example:
1- Fish meal and fish oil .
2- Fish selage.
3- Statakness processing.
4- Gelatine processing.
5- Fish skin and pons.
6- Fertilizer for aqriculture crops from fish oils.
The common errors occur during spawning of car
Here comes the importance of artificial propagation of carp species through practicing of induced spawning,
techniques in hatcheries under controlled conditions, whose products can be either a good quality (grow better,
tolerate better and convert feed better). The spawning season is stressful period for all carp species.
For successful artificial propagation we must be take care with the broodstock by good healthy, feeding ,
selection of species, transportation, acclimatization, injection, stripping. Also, good egg incubation in the hatching units
(optimum temperature, water flow, control and avoiding disease incidence and protection of eggs and fry from natural enemies).
Changes of fish after catch
On the death of the fish, processes of physical and chemical change caused by enzymes and micro-organisms begin to occur.
The complete decay of the fish is the final result of those changes.
Post-mortem changes which take place in fish tissue occur in the following phases:
- Slime secretion on the surface of fish: Slime is formed in certain cells of fish skin and the process
becomes very active just after fish death, Slime contains large amounts of nitrogenous compounds and these
provide good nourishment for micro-organisms originating from the environment. Therefore, the slime spoils
quickly: first giving an unpleasant smell to the fish, and second opening the way for further and deeper
bacterial penetration into the fish.
- Rigor mortis: Rigor mortis is a result of complicated biochemical reactions which cause muscle fibers to
shorten and tighten, and finally the fish becomes stiff. Usually, the later rigor mortis begins and the longer it lasts,
the longer are the storage life of the fish and its use for consumption.
- Autolysis and enzymatic decomposition of tissues: On the death of the fish, a complicated biochemical process starts,
leading to a decomposition of basic compounds of tissues which takes place under the influence of enzymes. This decomposition
involves proteins, lipids and carbohydrates. During autolysis, great changes occur in the structure of muscle tissue
which becomes softer.
- Microbiological decomposition:The muscle tissue of live fish is generally sterile but bacteria thrive in the alimentary tract
and on the skin, and from there they penetrate into the muscles, Penetration of bacteria into fish tissue and microbiological
decomposition begins with autolysis and these processes are practically parallel. However, their rate and intensity strictly
depend on the storage temperature. Low temperature strongly inhibits the activity of micro-organisms in which case the
autolysis process dominates.
Encompasses issues ranging in scope from global
national, watershed, facility, tank and finally to organism level.
At the shrimp farm level, biosecurity refers to producing healthy shrimp in a well-controlled environment
that excludes the introduction or propagation of unwanted organisms and includes the prevention or escape of organisms back into
the natural environment. The primary goal of a biosecurity program in shrimp farming is to prevent the introduction of any infectious
organism into a shrimp farming system. Since this is not always possible, the goal may have to be modified to prevent, eliminate or
control infectious diseases within the facility. There are numerous potential sources of entry for an infectious agent into an aquaculture
facility. These include additions of new stock (fry, post larvae, juvenile shrimp and broodstock); contaminated water or feed, humans,
animals or equipment, and subclinical (asymptomatic) carriers within the existing stock (production shrimp or broodstock).
Each of these potential sources needs to be evaluated and continuously monitored to prevent the entry of infectious organisms
into the system.