Water Quality Management For Aquaculture

Water sources is vital factors in aquaculture environment because the best water quality will results in high production yield with low rate of aquaculture problems. Proper culture management will ensure that the hatchery is free of disease. Disease can cause mass mortalities to the culture stocks at all stages. And as the reason, the disease outbreak will mainly from the water itself which is contaminated from where it initially comes or from any material used as well as from the surrounding air at the hatchery. The disease also can spread from contaminated feed for the stock consumption.

The hatchery infrastructure must be design appropriately and must allow cleaning and disinfecting activities to be carry out. The incoming water should be treated and disinfected through chlorination and filtration before it can be distributed to any different working areas at the hatchery. Distribution of water should also be designed to avoid any cross contamination. The water pipes, as well as the air lines, should also be set-up to allow overall cleaning and disinfecting and allow the disinfecting solution to be pumped in inside those structures and easily to complete the process during dry-outs session.

The most common primary filter in the hatchery is the sub-sand wells, which is used to filter raw seawater entering the hatchery. They are the favourable primary filter and they helps a lot in limiting fouling organisms, pathogen hosts, red tides and pathogens in which direct system is lacking. Next, the sea water must to pass through sedimentation process to remove any suspended solids especially any sediment substances.

The water is then to be chlorinated using hypochlorite solution (sodium or calcium) for 10ppm active ingredient for not less than 30 minutes. Chlorination is important in the water treatment to stun and kill any pathogens present inside the existing water. The next water treatment is through ozonation, UV light before the water is kept in the reservoir. The water in the reservoir must be checked to ensure there is no chlorine residuals remain inside the holding water. The chlorine test can be conducted using ortho-toluidine, 3 drops for 5mL of water sample. The water sample will turn into yellowish colour to indicate that the water still contains chlorine substance.

To deplete any chlorine substances left inside the water in the reservoir, sodium thiosulphate can be added at the same amount of total chlorine residue in the water (1ppm thisulphate to 1ppm chlorine). Before the water can be transfer to the reservoir, EDTA or any chelating agents should be applied to chelate any heavy metals which might present inside the water. The quantities of the EDTA is depends on the concentration of heavy metals present. For spawning and hatching tanks, extra EDTA is required at up to 20-40ppm to ensure that there are totally free of heavy metals and Treflan at 0.05-0.1ppm is applied to kill any fungi presences inside the water.

The water temperature for all tanks in the hatchery should come into consideration, as each area needs their own specific temperature to maintain their optimum growth and sustainability. Boiler, heater or any heat exchange system is required to increase the water temperature while a chiller system will help to decrease the water temperature. All these equipment must be installed just before the water from reservoir enters into the respective tanks. Each hatchery unit have different needs of water temperature. This is also applied for the size of the filtration used to filter the incoming water to the tanks.

The recommended standard sizes filtration and favourable temperature for each working area is referred as stated;

Working Area	Filter Size (mm)	Temperature (˚C)
Maturation Tank	15	28-29
Spawning Tank	0.5-1.0	29-32
Hatchery Tank	5	28-32
Algae Culture (indoor/pure)	0.5	18-24

Recommended standard mesh size of water filter and water temperature for each working area.

For hatchery with the re-circulating water system, cross-contamination can easily occurred between tanks and between every working area. To prevent this to happen, separate re-circulating system should be used for each area which required this system. This system is the most efficient system for broodstock maturation tank as they reduce the need for water replacement and residual water discharge. Re-circulation system helps to maintain stable physical and chemical parameters in the water. Besides, it also helps in concentrating mating hormones in maturations, as well as provides better biosecurity.

If the re-circulating system is employed, additional biological filters are required for each area of the hatchery as they are able to remove any dissolved organic materials found inside the water. There are many types of biological filters apply at the hatchery, where all filters are incorporate with living materials such as the denitrifying bacteria that must be cultivated prior to use, they are also require periodic cleaning in a way that does not kill the beneficial bacteria inhabitants.

For conclusion of the water quality management, it is important that all incoming water, tanks and materials must be cleaned, treated and disinfected before they can be distributed or used. Besides, all pipes and lines installed at the hatchery must be design to avoid any cross-contamination from occurred. Temperature and salinity most be control respectively to each area. The rules also applied to the filtration system. All of these methods must be accomplished to ensure optimum conditions are met at all time.

Fish Health Management Final Exam

minggu depan aku akan menghadapi exam akhir utk paper fish health management. tarikh blum confirm lagi, sma ada ahad, isnin atau selasa ni. subjek yg agak tough utk aku score semester ni..tp insyaAllah..dengan masa yg ada ni, aku akan lengkapkan diri sebaik-baiknya, mudah-mudahan aku berjaya macam yang aku peroleh semester lepas. nway, aku cuba gunakan kesempatan yg ada dgn menulis sedikit sebanyak overview of the course subject.

well, the course is about learning the disease which usually occurs either to the cultured fishes or to the wild fishes. earlier, fishes can be separated into many types or forms which usually came from the fish itself (teleosts or elasmobranch), crustaceans (shrimps and crabs), bivalves (clams, cockles, etc) and many other aquatic life (vertebrates or invertebrates).

diseases among the fishes especially among the cultured fishes is one of the main factor to affect the aquaculture sector of the entire world as they are known as the substantial source of monetary loss to aquaculturist. however, disease can be avoided if the fish health management with the best management practices (bmp) is applied at the aquaculture farms. BMP is the key of preventing any fish disease to outbreak. once the fishes are sick, it is difficult to salvage them.

Fish Health Management
successfulnes of the fish health management is measured by the proverbs of prevention is better than cure. preventing disease from outbreak is important rather than the treatment given to the sick fish. prevention of disease in the farm can be done by having good water quality, good nutrition, good sanitation and regular/daily observation of fish behavior and feeding activity of the fishes. disease among the fishes occurs by many pathogenic factors such as infections of bacteria, virus, parasites, protozoans, myxozoans as well as stressful condition due to many non-infectious factors (abiotic factors). many conditions is recognized as the medium of the disease outbreak; suboptimal water quality, poor nutrition and immune system supression.

medication treatment to cure any disease occurred acts as buying time for the fish and enabling them to overcome opportunistic infections. usually medication only success if implemented at the early stage of infections, where the fish is still in good shape. fish disease cause huge monetary loss to aquaculturist from the increased of production to cover the dead fish, cost of treatment, and if there are fish which survived, decreased growth of the fish during convolescence. high stocking density leads to the increases of stress among the cultured fish which increase the infectious of fish disease.

disease has strong relationship of pathogens, fish hosts and the environmental conditions for them to outbreak. the sickness among fishes is obvious sign when there are dead fish or dying fish. however, it is good if the observation can be done earlier as early as the fish is considered sick. fish is considered sick if they are not feeding normally and show lethargic motion. the sick fish might also hanging listlessly at shallow water, gasping at the surface and rubbing against any substrate. severe infection also shown by the presence of sores, ragged fins and any abnormal body shapes or structure of the fishes.

when the disease is detected, firstly, we need to check the water quality. low of oxygen and high ammonia content cause stress condition which lead to bacteria disease. generally, the DO, ammonia nitrite and ph level is the major physico-chemical water parameter to be checked. ideally, record keeping should be available because it can be the immediate references whenever the fish disease is occur. it will help to solve any fish disease problem. the record data should includes the date of the stocking fish, size of the stocking fish, source of fish, feeding rate, growth rate, daily mortality and water quality readings.

there are two major group of disease among the fishes which can be divided into infectious disease and non-infectious disease. infectious disease caused by pathogenic organisms found in the environment or carried by the other fishes. they are contagious diseases and can be controlled by some treatment. in contrast, non-infectious disease caused by environmental problems, nutritional deficiencies or genetic anomalies. they are not contagious, and usually cannot be cured through medication treatment.

however, fish disease outbreaks are often complex, involving both infectious and non-infectious processes. there are many public laboratories and institutional available to diagnose the fish disease. which can assist us in any problems regarding of the fish health. well, that is all i can wrote. it is not a complete but only the introduction of the course overview. there are still be more information to be discuss but i am too tired to wrote now. hope to continue again later..good nite..daaa