Grouper Farming Using RAS - Calculation 3

So long I was not able to update my blog. I was stuck with repair and maintenance works at my small project. Anyway, as promised we should carry on with another aspect of our RAS, i.e. to calculate the ammonia production, biological oxygen demand (BOD) and suspended solid (SS).

First, let we look at the food that we are going to fed our grouper fishes. Normally, if we are using commercial feed, we will know the level of protein content in the feed. The manufacturer will be proudly mention this fact on their packaging. Let say it was 40% protein feed that we are using to fed our grouper fishes. The calculation for ammonia will always be based on the nitrogen (N) availability in the protein. Based on molecular weight of the protein, we know that there are 16% of N in the protein in the feed given to the fishes. So, in 1 kg of feed, there are 64g of N (40% of protein/kg of feed x 16% of N in the protein).

If we know the body profile of our chosen species, we might know their protein content per kg of fish. Please do some literature review of your species to get this fact. In my case study, it was 20% protein in my grouper. Based on food conversion ratio (FCR) 1:1.5, one kg of feed will give 666.67g of fish weight. Therefore, per kg of fish, there will be 133g of protein (666.67g x 20% of protein/fish of 666.67g weight). Using the previous protein molecular weight, the N will be 16% of the protein, we will know that our 666.67g fish will have 21g of N inside their body (16% of N in protein formula x 133g of protein retain in the fish body). Therefore, our grouper fishes actually retain 21g of N from 1kg of feed that contain 64g of N. The balance 43g of N will be excreted out (64g in the feed - 21g retain in the body). So, we now may able to know the weight of ammonium produced / kg of feed by multiplying the amount of N excreted (43g) with 0.8 and we get 34g of ammonium produced per kg of feed fed to our fishes. In maximum standing stock (MSS) situation, the ammonium produced will be 3224g (based on maximum food given of 94.43kg) per day while in Average Standing Stock (AvStS) situation, the ammonium produced will be 2728g (based on 79.95 kg feed given daily). The amount of ammonium produced here is our concern and this is the burden that our bio-filter must solve before the water re-enter the farming tanks.

The biological oxygen demand (BOD) normally will be 500g for 1 kg of feed given. Therefore, in MSS situation, 47 kg (94.43 kg feed given x 500g BOD/kg of feed) and in AvStS situation, it will be 40 kg (79.94 kg feed given x 500g BOD/kg of feed). Based on experience, 250 gram of suspended solid will be produced from 1 kg of feed, so in MSS situation, our system will produce 23.61 kg of suspended solid per day (94.43 kg of feed given x 250g of SS/kg of feed) while in AvStS situation, it will produce 20kg of suspended solid per day (79.94 kg of feed given x 250g of SS produced /kg of feed given).

So far, we already able to calculate the consumption of oxygen and production of  carbon dioxide,  ammonium - N, biological oxygen demand and total suspended solid from our system. From these information, we will be able to calculate the design peak load of the system which will be used to determine the size of our bio-filter and maximum flow rate required to do the cleansing of our system.  I will try to discuss these aspects in my future posting.

Grouper Culture Using RAS - Calculations 2

In my last posting, we finally able to calculate the maximum standing stock (MSS) of our RAS for production of 12mt/year of grouper fishes. We should also be able to calculate the average standing stock (AvStS) of our system by doing the averaging calculation from month 1 of full batches production (i.e month 12 from the beginning of the farmig) to certain period of farming, which is based on my last calculation, I used to up to 16th farming month of full circle production, i.e month 26th. Let we see the table below:

Standing Stock

So, the AvStS will be 6149 kg through out 16 farming months and represent about 51% from targeted production. In my last post we calculated the MSS was at 7264kg or 61% from our targeted production. Bear in mind of these figures, which we will use to find the design peak load (DPL) of our system for most variables in our system i.e. oxygen supply requirement, carbon dioxide production, ammonia-N production, bio-oxygen demand (BOD) and suspended solids production. 

The maximum food given in MSS situation will be 94.43 kg/day while the average maximum food given in average standing stock (AvStS) will be 79.94 kg/day. The oxygen requirement for each kg of food given will be 350g while carbon dioxide produced per kg of food will be 1.2 times higher than the amount of oxygen consumed which is equal to 420g per kg of food given (350g x 1.2 times). Based on these facts, during MSS, the maximum oxygen consumption will be 33.05 kg/day while in average standing stock situation the oxygen consumption will be  27.98 kg/day. We also able to know now that carbon dioxide production in MSS situation will be 39.66 kg/day (350g/kg of feed x 94.43 kg of feed) while in average standing stock situation (AvStS) it will produce 33.57 kg of CO2/day (420g of CO2/kg of feed x 79.94 kg of feed). So, up to now, we already able to calculate our maximum standing stock, average standing stock, feed requirements during MSS and AvStS, the oxygen requirement during MSS and AvStS and lastly we able to calculate the carbon dioxide production in both situations of MSS and AvStS.

In next posting, I wish to share how to calculate the ammonia-N production, BOD and suspended solid going to be produced in our system.

Grouper Culture Using RAS - The Basic Calculations

Last week I visited 2 fish farms that using  recirculating aquaculture system (RAS). Interestingly, both have changed their species to another newly introduced species that having higher price and in demand in the local market. I like their idea of changing the species when the need arise. Having a better priced species is the rule of thumb no 1 in our RAS considerations, but surely is not the only factor that we must consider. More interestingly, they were changing from marine water species to fresh water species. That is the extra benefit of RAS. We may change the “climatic” conditions of our farming system without need to change the location or even the equipments.

What shall we know about RAS before we design it? First, off course the species that we intent to culture, their requirement or acceptable water quality. Please get the information on the acceptable levels of dissolve oxygen (DO), carbon dioxide (CO2), ammonia (NH4⁺ /NH3), nitrite ( NO2 -), nitrate (NO3-), suspended solids (SS) and salinity of our chosen species. Some grouper species have different tolerant towards fluctuation of the quality of some parameters. 

Second, we must quantify the target production over certain farming period (e.g: kg/month, mt/year). By knowing our targeted production, we may calculate the maximum standing stock (MSS), expected oxygen consumption and waste production from our system. We also will be able to calculate the water flow rate, solid and biological  filtrations systems. So, give our system a targeted production, say 12 mt/year.


Third, make a simulation standing stock for our 12 mt/year farm. Are we going to stock our juvenile in batches or all at one go? Say we are going to produce in 12 batches (1 batch/month) at 0.8kg/fish at 90% average survival rate. The survival rates for each month will be different. Normally, the fish survival will be higher when the reach bigger size. The farming period will be 8 month per batch. Therefor, we are going to stock  1280 fish juvenile/batch for each month.   If we are going to use fry of 50g each, in the first month we will have 51 kg of biomass in our system. Next month, with 83% of survival rate and average weight of 70, the same stock will grow becoming 158g each and the total biomass will become 168 kg. At the same time, the 2nd batch will weight 51 kg in biomass making total biomass in the 2nd month will be 219kg. The calculation goes on and on until we reach full 12 batches in the twelve month with biomass of 5034kg. Remember, we are going to sell our yield at the end of 8th month of each batches and restocking new fry in the next month. So, our calculation will results like this:

Standing Stock for 12 mt grouper farm with the Maximum Standing Stock (MSS). Table: Mahmud Ismail.

In order to know the highest standing stock of our system, we simulate the calculation until all batches in full operation. The highest standing stock for our system is 7264 kg which going to take place in the 16th month of operation. This value is called as Maximum Standing Stock (MSS) which indicates the highest load in our production in term of biomass of the fishes, maximum intake of feed and consequently the maximum waste formation. As can be seen, our MSS value is  around 61% of the targeted annual production.


Normally, we feed our grouper fishes around 1.2% to 1.5% of thier body weight per day (for calculation purpose, we use 1.3%). So, during the month 16, our Maximum Feed Consumption (MFC) will be: 7264 x 1.3% = 94.4 kg/day. However, in actual situation, the feeding rates varies according to the size of the fishes, at early stage (smaller size) the feeding rate normally higher then the feeding rate when the fishes are bigger in sizes.  


We shall continue later with calculation for oxygen consumption, carbon dioxide, biological oxygen demand (BOD), suspended solid and ammonia productions from this basic knowledge of MSS and MFC. Later, we shall also calculate the water flow requirement as well as the solid filtration system and the biological filter of our farm.  

Grouper Culture Using RAS - The Basic Processes

Without realising it, maybe most of us have been using recirculating aquaculture system (RAS) in our home aquariums for keeping our lovely ornamental fishes. So far, I rarely saw somebody using flow through system for their home aquarium. Did we study our aquarium system and how does it functioned to support the life of our aquarium fishes? If we did, perhaps it will be very easy for us to understand the RAS.

I believe everyone of us have some ideas about RAS, so I want to make the simplest explanation about RAS. The system work in a way where used water being moved into another cleaning system for cleansing purposes before being re-use back in the farming places. However, I used to see some system that do the cleaning process in situ, i.e. inside the farming tank itself. They move the water to some area of the farming tank and do the cleaning process before the water mixed back with the rest of farming water.

Why Go For RAS?
At least there are 5 reasons said in most of RAS textbooks on why people choose RAS for their fish (and aquatic organisms) farming system. Among the reasons is RAS can be operated in the unsuitable site for other type of farming. Since RAS normally a closed system, it will not depending so much on external factors. The internal environment perhaps can be "created" according to our species requirement. Second, it can be use in the area where water resources are poor, either in quantity or quality, either permanent or temporarily. RAS will not depending on external water resources to some extent. Third, it can be operated in the unsuitable climate for certain species. We can create our conducive internal climate in our RAS farm.  Fourth, we can control or have more control over our production.  Fifth, RAS can accommodate to environmental rules and regulations. However, for me, any other reasons such as logistic and market potential could also another reason why RAS was chosen. Personally, I choose the RAS because of the fourth factor, yes, I want to be in full control of my farm which I consider the most important aspect the fish farming management activities. I used to observe some other fish farming systems such as open water (sea, lake, lagoon and river) cages and ponds for groupers, seabass, threadfin, snappers, cobia and pompanos as well with molluscs and crustaceans. To my opinion, the open systems really can makes the management at the mercy of nature.

There will be few processes involved, mainly physical process in moving the used water into the cleaning place and physical, biological and chemical processes in the cleaning parts. We will see what are the processes involved in an recirculating aquaculture system (RAS) later (not including the biochemical processes that going to take place inside the body of our cultured organisms).

Function Of Water In RAS
As in the name of the system, it will recirculate  at least the water in the system (depending on how good the cleaning process of the system take place, otherwise, it will also recirculate some unnecessary element). Since we are keeping our groupers in the enclosed tanks, we must not only look at the water recirculating process   similar to air conditioning process in the a crowded places, but it work almost like the oxygen supply in the hospital intensive care unit. Our fishes will need the water as their living media and as their life support system. The recirculated water should bring along both basic functions, conditioning and life supporting. However, that 's not all the functions of the water in RAS. It will functioned as cleaning media for the system just equally to the same function of the blood in our body.  So, the recirculating of water will cover at least few processes: refreshing of living media, bringing in oxygen and cleaning the system.

The recirculating process in RAS normally done with the use of pumping system. We should discuss about the pumping system in RAS sometime later.

The Removing Of Unwanted Materials

When keeping our groupers in the tanks, they depends solely on the feeds given to them for their growth. We could be fully aware that every time we feed the fishes, there are some amount of the feeds were not eaten by the fishes. It will drop to the bottom of the tank, broken into pieces or swelled due to water absorption and some becoming the suspended solids in the water. At the same time, the fishes will excrete their metabolites through their feces. These will become our first problems, removing solid waste and suspended solid waste .After sometimes, the excess feed and faeces will disintegrated becoming smaller particles and require to be removed with other dissolved organic materials.

The breaking up of the uneaten feed will involve few physical and biochemical reactions or processes.The process of breaking up of feed and feces will require oxygen and this will creating demand for oxygen inside our system. Remember, our grouper fishes also require oxygen for their life and they also excrete carbon dioxide from their respiration process. 

The impact of the fishes on the farming water. Photo: Mahmud Ismail.

The eaten feed will be used by our fishes for growth and getting energy. In order to gain the energy, the feed components will be oxidized which will require oxygen and excrete carbon dioxide. Ammonia is another waste product of the breakdown of the protein in the feed. So, our fishes will consume foods and use oxygen for breathing and oxidation of the feed. The farming water will be the polluted with the uneaten feed, faeces, excretion of carbon dioxide and ammonia.

In the next posting, I will try to elaborate how cleaning processes being done in RASRAS or order from our supplier. Do not build or buy without knowing our real requirement of every components in RAS. We may end up building excessive or undersized components of our RAS. Since RAS is a life support system and life keeping system, anything below standard requirement will be hazardous to our grouper fishes while excessive mean more money needed for our initial investment, something that any investor will try to avoid.

Revolution, Earthquake, Tsunami And Grouper Spawning

Never likes last few weeks. My heart never have a chance to cool down. First it was revolution in Egypt where my son is now studying dentistry. For few days, we were not able to communicate with him. Sometime, no telephone, sometime no internet. The most scary times were when no internet nor telephone. While planning to take him out of that country and gathering information on security situation from the town his studying to the airport, then come the news of mass evacuation sponsored by Malaysian Government. My son was in the second last flight exodus from Egypt to Jeddah and the last flight from Jeddah to KLIA.

After few weeks at home, and the situation in Egypt seem stable enough for studying purpose, there come preparation for his departure. While preparing, and happily communicating with my daughter in Tokyo to celebrate her birthday on March 11, then the breaking news take place right in front of our own eyes. The 9.0 Mega Earthquake (2011 Tohoku Pacific Coast Earthquake and Tsunami) come right while we were speaking to her over Yahoo Messenger's video call. My wife able to see the doors swaying and the building shake, the sound of siren and advice my daughter to stay outside her hostel room until situation come to normal. After Friday prayer, most breaking news either by Japanese and international TVs shown the great effect of the earthquake and later how devastating the tsunami can be.

Looking at the ships and cars being moved by the great gush of water like small toys make my heart feel very sick. And the television footages shown some houses, factories and farmhouses covered by the hugh wave make everyone feel so sad, knowing very much there were human being out there that might be inside those ships, cars, buses, houses, factories and farmhouses that might be affected or drowned inside the mega wave. My daughter spend few sleepless nights at her hostel due to probability of another aftershock tremors  but it is not as bad as her friend who got to sleep at one restaurant because  she was outside during that time and all train services were stopped. Lastly, come the final blow of problem at the Fukushima power station which we hope and pray will not become another human tragedy in our life time.



The 9.0 Mega Earthquake and aftershock. Source: USGS

After the fourth explosion taken place at the power station, amid all the difficulties of getting one flight ticket I decided to take my daughter out from Tokyo and she was safely home yesterday. While having our late lunch together with all available family members at a restaurant nearby KLIA, talking and explaining about how scary the tsunami effects to the Fukushima power plant can be, my daughter who is number five out of six siblings ask me to stop, simply because she cannot take it anymore to hear all those effects of the nuclear radiation to human being. She complained feel like vomiting to think about such things. My wife still not settled and simply goes into tears every time the news of the situation in Japan goes on air, feeling so pity for those elders, children and families affected by the incident.

On Tuesday, one friend of mine told me that his Tiger Grouper broodstock spawned one day before the earthquake and tsunami in Japan. He collected 24 million eggs from 6 female TGs. Some fishermen in my area mentioned that one day after the Sendai's earthquake and tsunami,  the sea around our area seem to be very empty and quite, like no fish at all in the area. Is that just co-incident that almost all the TGs broodstock kept by my friend spawned a day before the earthquake / tsunami take place? Is that just co-incident that the sea around our area seem so quite a day after the quake / tsunami? I read news that some millions of sardine dead in California after the fishes swim ashore and later on dead due to lack of oxygen in the harbour basin, just two days before the earthquake. Could it be just another co-incident? We do not know the answer and what will be the effects of the quake and tsunami to life, deep in ocean and sea floors where most of our grouper species inhibits, but we know the effects to the human being that live on the surface.

To  the Japanese people, my heart and prayer goes along with all of you during this troubled period. We always look at Japan as our inspiration on how a developed nation should look like and believe Japan will come out stronger from this crisis.

Grouper Culture In RAS: The Introduction & Rule No.1

I saw a lot of interest on Re-circulating Aquaculture System shown by some visitors to this blog. My posting Introduction Of Recirculating Aquaculture System For Grouper Farming In Malaysia seem to get the most hits from the readers. In that posting, I did mentioned my wish to give my observations on the RAS that I manage to see in this country. I hope to be able to do so sometimes later. For now, let share the information on the system.

My initial exposure to RAS was way back to early 1990s when some grouper farmers in East Coast States of Peninsular Malaysia used to face high fish  mortality due to heavy rainfall during monsoon season resulting in heavy losses to them. I must say, it was too early to think about RAS during that period of time when even cage culture system was considered the most "modern" technology of the day. Later on, I get involve in cage culture of grouper fishes, only to confirm how inconsistent environmental factors will greatly affect the production as well reduce the management efficiency to the lower level with a lot of uncertainty and out of control conditions. It may frustrate even good and dedicated managers.


Abalone farming using RAS.
 Photo: Mahmud Ismail

I still remember a simple book but with very informative content published by INFOFISH with the title Recirculating Aquaculture Systems which I seriously consider as my text book during that time and remain relevant until today. (You may purchase this book on line now from INFOFISH Publication). Since then, I have seen many RAS farms in operation in many parts of the world, some in fully automatic system complete with additional support systems while others just basic RAS and some called their system as semi RAS.

High density turbot farming using RAS

One of the system that I want to mention here is an eel farm in Denmark which I visited way back in 2002 that have a production line from hatchery to finish products. The farm is using a fully automatic RAS with very minimum workers can be seen around but the fish seem to be being properly being taken care at every minutes during the farming period. In each tanks the water parameters were monitored automatically using probe sensors and reported to the control room in real time. There is no one at the control room either. Should anything odd taken place, the system will trigger the manager's and supervisor's mobile phone. To add to the sophisticatedness of the system, they are using green energy, by using wind turbine generator to supply the energy to their farm!

Another system that I always remember when RAS issue arise is a farm in Spain which I visited by the invitation from a friend from Tromso University, Norway. The farm always remind me of Stadium Melawati in Shah Alam Selangor because partly, that's how it look like. The farm contain circular tanks at various level. During my visit, they were farming turbot with capacity around 500 mt per year. They were using photo stimulant to enhance the growth of the fishes, play with gravity forces to reduce the pumping costs and the  fish physiology to do natural grading of the stock.

Mouse Grouper could be a right species for
RAS system.

Since introduction of RAS in 1970s, so much progress has taken place in this technology. Due to global pressure in marine capture fisheries and environmental problem in pan and cage cultures this system gaining popularity in many parts of the world. In the book, Urban Aquaculture (Cabi) some writers considered RAS could be the answer to the need for environmentally sustainable production of marine farmed organisms. However, since the initial and operating costs in RAS are higher as compared to pond, cage or pan cultures, anyone who want to invest in RAS must seriously consider the kind of species they wish to culture in order to achieve economic return on the investment. Generally speaking, we should go for higher price species if we are using RAS. Nevertheless, economic of scales in slightly lower priced species could also bring a positive results.

I always consider some grouper species are economically viable to be cultured using RAS. So, our first rule of thumb in choosing either to use or not to use RAS is the economic viability based on the price of the chosen species. 

Genetically Improved Farmed Groupers (GIFG)

There always some inspiration when I look at salmon industry. The industry growing in a very focus way to improve its productivity, efficiency and reducing the effect of potential problems. a lot efforts has been done to perfect the industry in various aspects. One of it is the genetic improvement of the farmed salmon strains. Recent report by FishUpdate  dated January 31, 2011 mentioned on the progress of study in Infectious Pancreatic Necrosis (IPN) virus resistance gene in salmon. IPN virus is  a major killer for commercial salmon farming especially for young fishes all over the world.

The researchers from University of Edinburgh, Institute of Aquaculture at University of Stirling and geneticist from Landcatch Natural Selection Limited (LNS) in United Kingdom manage to find this gene. In 2008, they published the evidence of an IPN resistance gene which is beneficial to prevent death of salmon from IPN. For the first time in aquaculture, LNS used marker assisted selection, an advance form of selective breeding, to improve resistance to IPN in their commercial strains. Further study now going on to find the precise location of the gene in the salmon genome and to identify additional genetic markers closer to the resistance gene. These Single Nucleotide Polymorphism (SNP) markers used to select the IPN most resistant fish for breeding. Their works surely shown a way for researchers in grouper industry to apply such leading-edge genetic and genomic technology in grouper's genetic selective breeding to help farmers to get a better strain for fast growing, disease resistant and highly demanded grouper fishes.



Hybrid between female tiger grouper and
male giant grouper.

 So far, not much result of groupers genetic research available in this country or even from this region. However, I must pay my respect for the best work done by some researchers in cross breeding of Giant Grouper (E. lanceolatus ) and Tiger Grouper (E. fuscoguttatus). Although this finding was not based on the work at gene level, I would say it is seriously a good achievement and should deserve all the credits. The output of this hybridisation technique currently in high demand in the market, getting very good price and acceptance at the consumers level.

Tilapia nilotica: Original and modified to suit the
colour's preference of the oriental markets.
Photo: Mahmud Ismail 

Last few years, the tilapia farming got a boost from the introduction of Genetically Improved Farmed Tilapia (GIFT) which brought good results in term of growth rate and flesh recovery which helps thousands if not millions of farmers around the world. I love to see such development in grouper farming. Since we do have good example from other farmed species, the chances of duplicating such process to the grouper species seem to be very natural way of getting the fastest results, before more serious works take place. Off course the situation of tilapia culture seem to be more easier than groupers culture due to single species (Oreochromis niloticus) needed to look into in the case of GIFT.

Since early of this millennium, some researchers already emphasize the need for further research on genetic improvement for the grouper species. I flip through some papers presented in one workshop on grouper aquaculture back in 2002 ( you can download it free for your own leisure reading from Proceeding of Grouper Workshop) and found suggestion from one presenter that emphasize the need for genetic improvement of the cultured grouper species. In this region, I saw some works on genetic improvement for grouper have been carried out in neighboring country but actual result from the study still not yet being published.

Should we become one of the scientist studying the genetic improvement of the grouper species, what could be our priority to look into? Perhaps the fast growing gene in Mouse Grouper, low salinity tolerant gene in most of grouper species, VNN virus resistant gene or something like new hybrid between Giant Grouper with Coral Trout? As for me, most probably I will go for fast growing gene for Mouse Grouper and Coral Trout. Perhaps, I will produce another version of GIFT for these kind of groupers. Can we call it GIFG?