WATER QUALITY TASTE IN FISH FARMING

Find out what, why, and how to
monitor critical water quality
parameters to ensure animal
health and growth so you can
reduce costs and wastes by kINGSWAY AGRO SERVICES. The task of the commercial aquaculturist is to create a stable aquatic environment that reduces
the energy that fishes, crustacea, and mollusks must spend simply surviving and increases the energ
available for growth. Aquatic
animals must rely on the water
that surrounds them for warmth,
oxygen, and food. They become
stressed when key parameters, such as pH, temperature, dissolved oxygen, and salinity, are not withi their optimum range for survival.The effort it takes these animals stabilize their bodies in a stressful environment increases their energy consumption. This, in turn increases the demand for and cos of food while retarding growth.
The animals may eventually even
die. In addition to its effect on
energy consumption, a stressful environment can also predispose
an animal to, or even cause,
disease by creating conditions in
which microbes thrive while the
animal struggles. To ensure the
water quality parameters are kept within the optimum range for the
species being cultivated, frequent
monitoring and necessary
adjustments must be made. Myron
L Company manufactures handheld
instruments and monitor/ controllers that measure, monitor
and control a variety of
parameters that affect the
wellbeing of aquatic animals and
the profitability of farming them.
Parameters include pH, Temperature, Mineral/Salt
Concentration, TDS, Conductivity,
and ORP/Redox Potential. pH The pH of the water aquatic
organisms live in affects the
concentrations of dissolved
substances, the physiological
functioning of the animals, and the
other plants and animals in the environment that provide food
and oxygen to the ecosystem. A low pH will increase the toxicity
of dissolved metals and may cause
phosphate, sulphate, potassium,
and even calcium to exceed
accepted levels. In waters with a
lower pH, the ionized form of ammonia is more prevalent, which
is less toxic. Beyond pH 8, ammonia
can become a problem. An accurate
measurement of pH is also useful in
deriving the concentration of
ionized ammonia from total ammonia at a given temperature.
pH also influences the need for
liming in ponds. If the pH is greater
than 8.5, liming is not required. pH impacts physiology, for
instance, by affecting the ability of
blood to carry oxygen in finfishes.
pH tolerance ranges vary according
to species, size, and life stage. For
example, eggs and young fish are more sensitive than adults. In
addition, adults are more sensitive
to pH fluctuations during their
reproductive season. A typical
range that is suitable for
freshwater fish production is 6.5 to 8.5 (as measured at sunrise in
ponds). Crustacea and mollusks
require a pH between 7 and 8.5.
Marine animals generally require a
pH range of 7.8-8.2. Because pH can fluctuate wildly in
freshwater or unbuffered systems,
you have to monitor and control it
carefully to create a stable system.
Pond water pH should be measured
at sunrise and then once every two to three hours throughout the day
until sunset to get an idea of the
pH range of a particular system.
This is important because pH varies
throughout the day and night due
to photosynthesis of aquatic plants and other environmental
conditions. Cloud cover can
decrease the activity of plants and
hence, the pH. So, too, does acid
rain. A dense algal bloom may
increase the pH as carbon dioxide is consumed and oxygen produced.
Myron L Company manufactures
instruments for on-the-spot
readings of pH and monitor/
controllers to adjust pH
automatically. The Ultrameter II and the POOLPRO are handheld
meters that measure pH precisely
at the press of a button. Results are
displayed on the digital screen
instantly and can be stored in
memory for easy record-keeping. The 720 Series II pH Monitor/
controller is ideal for establishing
and maintaining an acceptable
range. You can easily configure the
unit to open and close valves that
control the release of pH-adjusting chemicals whenever the pH
exceeds the setpoint. This ensures
that regardless the conditions,
water pH is safe for animals. Temperature All species of aquatic animals have
specific ranges of tolerance for
temperature and optimum ranges
for growth of body tissue.
Temperature controls the rate at
which food gets converted to energy, which affects respiration,
food intake, growth, and behavior. Temperature also affects the
amount of oxygen dissolved in the
water and the existence and
growth of organisms that cause
disease. An increase in
temperature decreases the dissolved oxygen while increasing
the metabolic rate, which, in turn,
increases the animal’s oxygen
demand. Harmful aerobic bacteria
multiply rapidly and compete for
the limited oxygen. In finfish, heightened activity increases the
fish’s production of carbon
dioxide. This lowers the pH of the
blood, which can lead to death.
Regardless, extreme temperature
will eventually cause fish to slip into a coma. Temperatures below the survival
range cause the gill membranes in
fish to become permeable. The salt
pumps in the gill stop working, and
the kidneys fail. Metabolic rate,
respiration, and heartrate are reduced and red blood cells lose
their ability to carry oxygen.
Resistance to diseases declines
while the population of pathogens
may not. Crustacea and mollusks are less susceptible to thermal stress than finfish, but rapid changes in temperature do not allow these
animals to readjust their internal
chemistry to the environment
either. Any temperature changes
should be monitored and
controlled carefully in increments of 5ºC. It is generally best to keep the
temperature of the water toward
the lower end of the optimum
range for growth. The Ultrameter
II and the POOLPRO measure and
record temperature with highly accurate thermistors located in the
cell cup each time a sample is
taken. All 720 Series II Monitor/
controllers with digital displays can
be used to monitor and control
temperature automatically by increasing flow rates to cool water
or decreasing water levels to warm
water. Mineral/Salt Concentration, TDS,
and Conductivity Conductivity is the measure of the
total electrical conductivity of
dissolved inorganic ions in water,
which includes those ions that
contribute to alkalinity, hardness,
and salinity. Total Dissolved Solids (TDS) is determined in parts per
million or thousand based on the
measurement of conductivity and
the calibration of the instrument to
the predominant make-up of the
water. Mineral/Salt Concentration gives parts per million or thousand
as well. A conductivity reading is usually
taken in aquaculture to get a general idea of the hardness of the water. A low conductivity reading may indicate soft water, whereas A higher value may indicate
hardness. Crustacea and mollusks require calcium carbonate for their exoskeleton and shells, and so prefer hard water. Water hardness
also affects freshwater fish
osmoregulation. Water with a hig conductivity or TDS/Min/Salt reading has greater salinity —
more like that of the animals’
blood. This reduces the effort it
takes to replace lost ions from the
blood. A salt solution made of 8
parts per thousand will decrease stress in fish in transport to and
from ponds. In general a TDS of
1000 ppm is tolerable to aquatic
organisms in freshwater
environments. For the most part,
marine organisms are adapted to levels of 35,000 ppm, but marine
environments can vary from
20,000-60,000 ppm. Use the Ultrameter II and the
POOLPRO to measure dissolved
solids by Conductivity, TDS, or Min Salt concentration on-the-spot an the 750 Series II to monito control
concentrations automatically. Myron L produces solutions of
potassium chloride and sodium
chloride and our own special 442
formula to most precisely calibrate
the conversion of conductivity to
TDS in a given aquatic environment. Call 08032861326.

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