The best and most convincing reason for believing that researching the use of high oxygen levels to grow many species of aquatic vertebrates and invertebrates that I recall was at our 4th pilot project built at Piny point palmetto about 20 years ago where I had a stocking density of approximately 5-6 pounds per cubic foot.
We had the water recirculating through two large tanks that were approximately 40 feet wide and sixty feet long separated by a 10 foot wide walkway.
We injected oxygen into the water as it entered our u-tube and create high oxygen water by running it through a large u-tube I had constructed on my property.We were able to achieve an average of 100 parts of oxygen in the water coming from the u-tube, going into each of the production tanks. When I climbed into a tank with our oxygen meter which had been modified to read up to 200 parts per million so we could get an accurate reading on the water coming out of the injection pipes into the growing tanks.
At first the tilapia seemed a little more frisky which I felt that the tilapia were happier.
Several weeks later we turned up the oxygen being injected so I gradually increased the oxygen rate and observed how the tilapia behaved in these tanks.
When the oxygen in the tanks reached an average of 8 to 9 ppm we stopped the increase and found that the tilapia ate about 3 feedings a day and ate all of the feed. The feeding rate was calculated to feed approximately 3% of the bio-mass over each feeding day.
I believed for various reasons that the fish could eat the same weight of feed as the oxygen injected and dissolved, this feed should not exceed the total weight of 32% protein feed which matched the weight of dissolved oxygen fed into the water supporting the tilapia.
If the weight of feed added to the tank was more than one to one, that is one pound of proper feed per pound of dissolved oxygen kept the tilapia well fed but 1.1 pounds of feed fed to the tilapia brought risk to the water quality of the tank.
So when our goal was set to add enough oxygen the number chosen which seemed to work was one pound of good feed to one pound of tilapia.We set the low point for the oxygen injection to match the amount needed for feed and then anytime the dissolved oxygen dropped below 8 ppm the extra oxygen was injected as long as the reading remain below and an alarm sounded for the operator to check the system.
The injection of oxygen to be dissolved was set on the automated oxygen monitor to open a solenoid to allow an additional amount into the u-tube which was about 50 % more oxygen than was being fed. this solenoid valve remained open until the oxygen reached the high point desired.
We generally set the low point of 12 ppm when the oxygen dropped lower than that the booster with the flow rate of 50 % of the constant flow rate came on. This generally was enough to reverse the trend but when the oxygen dropped below 8ppm the alarm cane on which generally activate a second solenoid controlled valve and allowed the injection of oxygen to double.
Using this hierarchy we were able to hold higher levels such as the 12-14 ppm level and found that the tilapia we deliriously happy and could consume the largest amount of feed per tilapia. They were
e always healthy and hungry which is my measure of tilapia happiness happiness.
That system is shown at the address for you-tube where you can type the words “ cherry” “ snapper an” you will view a video taken of the system. You will see happy fish “tilapia” voraciously attacking the feed.Coincidentally the hybrid being grown in that video were called “happyfish” due to their broad body form and the parent breeders which were from the red-red tilapia Mozambique gene line and so were named the red-butterball pennyfish.
All of these experiences occurred about ten years ago. So our 10 year old video unveils the relationships. Looking at this video makes me remember a lot about the relationships between Tilapia and oxygen.
My summation at this point is that having a high oxygen level enhances the health and growth of tilapia. The amount of food stays about the same. It takes approximately 1,5 to 1.7 pounds of quality feed to get each pound of whole tilapia, this seem to be the same for every species and is not effected by the oxygen level. Tilapia require oxygen to metabolise the food that they eat and the higher levels improve the growth rate. Our hybrid pennyfish (tilapia) grow from 10 grams each to half a kilogram in 16 weeks in a system which holds the oxygen level between 10 and 14 ppm. The reason seems to be that the availability of oxygen is higher during periods that it would ordinarily fluctuate from 14 ppm to zero ppm in a pond. This fluctuation stresses the same tillapia in natural systems because the availability of oxygen all of the time extends the feeding periods so that the tilapia eat and are able to metabolise more feed over 24 hours in warm water and so grow much faster than they do in natural systems.
My reaching the age of 70 enhances my ability to draw conclusions from all of my work and the need to communicate these conclusions with other peopleA further benefit of being 70 helps me to apply some of he basics of what I have learned about the need for oxygen to other life form, all other species of aquatic vertebrates, and of all other aquatic life forms.
As of yet I have found no flaws in my opinions, in that I believe that any animal that metabolises food using oxygen can do so for longer periods during a day.
That is, If the oxygen level is held at a higher level at all times.
Since the metabolism of food seems to be cheaper from a total energy point of view if oxygen is available and the metabolism is aerobic instead of anaerobic.
So if oxygen is readily available and the total energy is therefore used for aerobic digestion then the animal will grow more using aerobic digestion, than the animal will using anaerobic digestion, that is, if they have that choice.
Tilapia tilapia have that choice and can metabolise food aerobicly or anaerobicly, and tilapia do so most efficiently during aerobic digestion than during anaerobic digestion.
So, it only stands to reason that if the equipment is available for supplying inexpensive dissolved oxygen that nearly every aquatic vertebrate or invertebrate will consume more food and grow faster.
That means that if we can develop a system for supplying dissolved oxygen we can improve the growth of many, many aquatic species.Another Test I ran many years ago which anyone can repeat for very little money.
Put 20 or thirty 2 to 4 inch tilapia in an aquarium that has been heated to 85 degrees and aerated for several days.
Set up a video camera to record what the fish do while, at the same time, you have a video camera focused on the aquarium place the read out of an oxygen meter in the bottom of the video cameras view so any changes that are made will show in the video.
Place an oxygen tank near the aquarium and rig up a tube from the oxygen tank to one of the air stones and place a thermometer in view of the camera too.
Put at the tilapia in tilapia in the tank. Drop the oxygen probe about half way down the glass.
Calibrate your o2 meter and turn on the read-out of the o2 meter. make sure you have the oxyge meter reading in the cameras view.
If you have been putting air into he tank for a couple of days the reading should be around 6 to 8 ppm.
This is considered the upper limit to supplying oxygen by pumpin air through a sparger that breaks up the air in the water.
Take about a teaspoon of high protein sinking fish food and drop it in the view field of the camera.
Watch what the tilapia do.I used a sinking feed that is about as big as my thumb that was about an inch in legenth. This feed went right to the bottom. The feed was hard when dropped in the aquarium but in just a minute became soft and when the tilapia went in for a bite they were able to bite off small chunks and would then swim away with the food in their mouth sort of chewing it.
Soon, about 5 minutes to ten minutes later, at an oxygen level of 8 ppm, each fish would return to the fish food pile and take another bite. If you make a pile of food about an inch or so high that you would think they could not eat it in a day.
with an oxygen reading of 8 ppm each fish would come back for another mouthfull, then swim away to another part of the tank.
For any questions on fish or fish farming email Mike direct on miketsipe@gmail.com
Source: cherrysnapper
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