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S-92 SEQUENTIAL FISH CULTURE SYSTEM
1. What is meant by Scale of Economics in an aquaculture system?
A. Scale of economics in the simplest terms means the number of pounds of fish or
quantity of fish needed to be produced and sold at the current market price to pay all
cost of the operation and make enough profit for the owner- operator. In general the
smaller the system, the more it costs to build and operate per pound produced. This is 4
because certain fixed costs remain the same no matter how many pounds are produced.
For instance, assuming that the owner of a system pays an employee $24,000 per year
to work for him. If the employee is operating just one tank of fish, then the cost per
tank per year is $24,000. However, if that same employee is operating 24 tanks then
the annual cost equals $1,000 dollars per year per tank. The same goes for equipment
installed in a system. If, for instance, one filter unit costing $6,000 will operate from
one to ten tanks of fish and only one tank is installed, and the tank will produce 6,000
lbs. of fish per year, then the initial cost of the filtration is $1.00 per pound for the
first year's production. However, if ten tanks are installed the initial cost of the
filtration is spread over all ten tanks and the cost is only $ .10 per pound of annual
production. In other words, the more a system produces, the less per pound it costs to
build, operate and maintain it, thereby creating a higher margin of profit. It is for this
reason that we explain that a system must produce approximately 200,000 lb. per year
for the owner/operator to pay all bills and still make a good living exclusively from fish
sales from the system.
2. Are there any benefits of using rectangular tanks over round tanks?
A. We think so. It must be remembered why anyone uses round tanks in the first place. A
round tank is really just a cylinder holding the water. Because water exerts pressure
equally in all directions when placed in a cylinder, round water vessels can be
constructed very cheaply using the minimum thickness of materials. The advantages of
this fact is, round tanks can be transported to a site and quickly set up. However, this
convenience is the only quality of a round tank and this lends no particular advantage
where production is concerned. It should be remembered that it is production that pays
the bills and the fact that the tanks were easy to install should not be allowed to over
shadow future performance. The most obvious first drawback to a round tank is they
are space intensive. A round tank in a rectangular room means there is going to be a lot
of wasted space in that room in the corners that the tank does not cover. Another draw
back is the fact that a round tank has no difference in length or width, therefore water
circulation can only occur in a circular motion. Many early designers use to explain
that this circular motion was the most effective way to remove solids, because the
vortex in the center acted like the vortex in a toilet. They obviously flunked out of
physics class because the two vortexes are caused by different dynamic effects. In a
toilet the vortex is caused by gravity. This occurs when the valve is flushed there
is a sudden opening at the bottom of the bowl. As the water drops through the hole,
gravity and the Earth's rotation take control and causes the water to swirl around the
void left by the water that has already escaped through the bottom. This causes a
partial vacuum at that point and sucks everything into it. In a round tank the circular
motion may resemble a toilet vortex, but instead of being caused by gravity and a
partial vacuum, it is being caused by water flow from a pump. This water flow is
greater on the outer edge of the tank then in the center, therefore a certain amount of
the solid waste in the tank will travel towards the center. However, the problem is,
waste deposited along the outer edge of the tank may have to orbit the tank hundreds of
times before it finally makes its way to the center. In the mean time it is being churned
and homogenized the entire time and can cause water quality problems as it slowly
disolves. In a rectangular tank the water flow is generally in a straight line from one
end to the other. This would mean that a solid deposited in one end of a 25 foot long
tank can only travel 25 feet, and in one direction, before it hits the bottom solids trap.
In most system designs the time required for the trip may only be a matter of minutes.
Therefore the solid is removed in it's entirety before it has a chance to dissolve in the
water column and cause water quality problems.
3. Since the S-92 system utilizes a central filtration system for all tanks in the
system, doesn't this mean if one tank of fish get a disease eventually all of
the tanks will get it?
A. Not at all. First it must be understood what causes a fish or any other living animal,
including humans to get sick. What we call sickness simply means that for some reason
the conditions got right for some virus or bacteria to attack a fish. Just as people are
constantly surrounded every minute of every day by cold germs and other viruses, the
same is true within a fish culture system. A normally healthy person has enough body
strength and immunities to continually ward these viruses off. As we know, in cold,
wet weather a person is more likely to catch a cold because the adverse weather and
climate conditions can stress a person's immune system and leave them vulnerable to be
attack by these pathogens. Many people move to more favorable climate areas to lower
their chances of getting sick. The same is true within any fish culture system
whether it be ponds or tanks. The fish are constantly surrounded by what are referred
to as, "Opportunistic pathogens". These "Bugs" are just waiting for a fish's immune
system to weaken, for any reason at all, and then they attack the fish and take over.
The way to prevent a fish from weakening is to prevent stress. Stress in a fish can
come from a number of things including poor water quality, sudden changes in
temperatures, poor oxygen levels, poor surrounding environmental conditions such as
outside noises or sudden changes in lighting levels, and a host of other conditions
adverse to the fishes peace of mind. We have, during experiments on the subject,
taken several dozen deliberately stressed and weakened fish and placed them into a tank
of 2000 healthy fish. Within days the stressed, sick fish were dead and floating on the
surface, but the healthy resident fish, who had not been stressed, continued on as
though nothing had happened. Once again, the most important factor to consider
concerning fish health is, "Keep the fish happy".
4. Are expensive computer and monitoring systems really necessary in fish
culture?
A. No. But then again, the insurance on your house is not really necessary for the
purpose of living in the house either. However, if your house burns down and you
have insurance, then it turns out to be a good investment. Computer monitoring and
controls serve two main purposes. First of all, computer monitoring allows the
operator to evaluate the conditions of the system at all times, even when he is not at
the facility. By watching trends he can keep the environmental conditions at a level
that will eliminate the stresses mentioned above. Also, by keeping track of the
conditions he can get maximum growth and production performance from the culture
and keep his operating cost in line. However, there are many people operating systems
without this type of monitoring who do very well because they spend a lot of time on
the job working with the fish. For a hard working, dedicated owner/ operator this is
acceptable. However, in a situation where the owner is depending on employees who
may not be quite so dedicated and are only waiting for quiting time each day, it pays to
have a computer keep records. One part of controls that a serious operator cannot work
without is a monitored alarm system. This is like the insurance policy. Since the system
is made up of many different life support devises it is imperative that these be watched
at all times, twenty four hours a day. Obviously, it is not possible to keep a human eye
on the conditions at all times, therefore we must depend on sensors to watch for us.
These sensors usually watch only oxygen and water levels. The first time the sensors
warn the operator in the middle of the night that the oxygen levels in a tank have
dropped too low they will have paid for themselves by preventing the loss of a valuable
crop. 
5. What type of fish should I raise?
A. Aquaculture is basically a manufacturing business. As with any manufacturing
business a person must produce a product that he feels has a good demand in the market
place and will produce a good return profit. Aquaculture is generally spoken about in
the press as the production of food fish. However, aquaculture includes anything that
is raised in a water environment. As far as finfish are concerned, they can range from
food fish for human consumption, ornamental fish for home aquariums, or baitfish for
the sport fishing industry. It is up to the individual operator to examine the local
market potential and determine what area he feels would be best to supply. One thing
that many people ask about are various types of known food fishes that are caught in
the wild such as flounder and cod, etc. These deep water ocean fish are not now, and
probably will never be the most productive animals to raise in captivity. There are
many fish such as Stripped-Bass, Tilapia, Catfish, Trout, etc., that have proven to be
good species to grow in artificial environments. It is these species that should be
concentrated on. As aquaculture slowly replaces wild catch species as the main fish
supply source, consumers will eventually find preferences for one or two main types
of aquacultured fish and it is these species that will dominate the market and become a
staple in the family diet. At this time the Tilapia shows great promise of becoming the
dominant species (although this could change someday with the development of a new
breed). In some areas Stripped Bass have a good market and of course the Catfish has
continued to have increase demand each year. For many owner/operators, especially
those doing their own marketing, it may be wise to grow several different species of
fish in order to better serve their customer's request.
6. How much money can I make in aquaculture?
A.The answer can vary greatly depending on many factors, none of which necessarily
have anything to do with volume produced. As far as volume is concerned there are
many records of systems being built that were designed to produce millions of pounds
per year, but they proved to be a financial failure. On the other hand, there are
hundreds of small operations run by family members that are a financial success. First
it must be recognized that there are may layers to the marketing of fish to the
consumer. A farmer selling his product to a wholesaler will generally receive only
about 50% of the amount that a store will eventually sell it to an end user for. This is
because both the wholesaler and the grocer have added a percentage markup to the
product. The highest profit for a farmer will be when he sells directly to the end user,
be it a housewife shopping for the family or a restaurant owner buying for his menu. It
is the same with baitfish and ornamental fish. A sport fisherman may pay $3.00 per
dozen for bait minnows from a dealer who paid a farmer $2.00 per pound for the
minnows which contained 36 or 50 per pound. Therefore, a farmer selling directly to
the fisherman is going to make more money. It is exactly the same for ornamental fish
growers. For farmers growing 100,000 lb. of fish per year the buyer is usually a
wholesaler. The wholesaler will further distribute the product and perhaps do the
processing. Under these circumstances the farmer can generally expect to profit
between $.25 and $.50 per pound for his product. He can further enhance his profits by
selling a portion of his product direct to the end users such as restaurants who will come
to the farm and make the purchase. This is where the scale of economics comes into
play. Based on the above mentioned profit per pound, a farmer producing 200,000
pounds per year can achieve a take home pay of $50,000 plus per year. Of course
another factor concerns the efficiency of the operation. A farmer running a poorly
managed operation with a large mortality rate or feed waste is growing to lose several
cents on every pound of fish he produces.
7. I have an idea for my own design. Will any of the componets found in the S-92 System work for me?
A.In most cases the answer is yes. But the question is, what have you designed? If your new design includes a complete filtration system, then of course you don't need ours. However, if you are in need of bio-filtration, then we can help you. It would be the same with the oxygen injection system. many of our componets can be retro fitted around a different design. We recomend that if you are designing a system of your own you send us the details (all information is confidential) and we will evaluate the design and tell you if any of our componets will enhance it. (Yes, we have seen many unique designs that we could not use anything we make) . This evaluation service is free for the first inquiry. The same thing goes for people who have older systems and who would like to up-grade them.
aquatic@iximd.com
Copyright 2000
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All information found throughout these pages are the exclusive property of Global Aquatics Ltd. and may not be copied or distributed without the expressed written permission from the owners of this intellectual property.
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