Learn the secrets of a successful fishfarm. You will smile to the bank!

What differentiates a prudent fish farmer from a novice in the fish farming business? Why do some farms make more money and experience fewer hazards in their farms?

a good stocking density equals to more profit for the fish farmer

These are some many questions that fish farmers ask themselves, at various times on their journey in the aquaculture industry.  

What differentiates a prudent fish farmer from a novice in the business is this; that the prudent fish farmer knows that if he stocked his fishpond with just the right number of fish, at the right stocking density; his fish will properly utilize his feed for growth and defense against infections and diseases. the novice onotalks the other hand; talks of big numbers, but only has a few ponds, so he over stocked them, exceeding their stocking density. He later experiences a deadly outbreak caused by a bacterium, and he lost half his stock in a matter of days. 

95% of the time, you find that; such a loss was inevitable because of poor farming practice, and lack of technical knowledge of aquaculture.

a successful farmer is always happy

To archive success in fish farming you have to know how to calculate the stocking density of your fishpond. So the big question is, how do we calculate the optimum stocking density of a fishpond? Let's find out.

Many attempts have been made to determine the optimum stocking density for catfish clarias garinpenus, such as would yield maximum productivity. While various mathematical models have been created for calculating the optimum stocking density of catfish in various culture systems, the local application of such models becomes a problem because of certain factors that are variable. By variable, I mean that, these factors change.

I myself have been curious to know the right stocking density for catfish, to help my clients make better use of their pond space to the maximum fullest.

Each time I construct a fishpond for a client, one of the services I provide them is to tell them the capacity of their ponds in Volume i.e. Liters; this is because, it helps them to calculate their stocking density, not to exceed the capacity of the pond, and at the same time, run into loss because food would be wasted.

The right stocking density equals to good growth of your fish stock, and proper feed utilization for growth, which as well equals to, profit for the farmer and more money in his/her bank.

What do I mean by all this?

Many are the problems in catfish farming, that are caused by the stocking density of a pond been exceeded.

I client of mine stocked 1800 fingerlings, and separated them in three 3000L capacity fiberglass tanks: pond 1, 2 and 3. After a month the fishes started recording fatalities in pond 1 and 2, but the bulk of the fish kill came from pond 2 in particular, while the fishes in pond 3 where responding well. From my observation, I could see that the pond that recorded the most death i.e. pond 2, also had low growth, and most of its population had cracked skull deases. I saw from my observation that pond 2 had the highest population of fish followed by pond 1.

Now as a professional, I sometimes like to watch and observe my clients and their farming operation and farm practice, while I keep my comments and suggestions at a minimal.

As a continued to observe, I noticed that the other fish population in ponds 2 and 3, recorded least deaths, and had the most growths, especially pond 3.

From the above analogy it is clear that something was clearly causing the problems. Pond 2 was overly stocked and as a result, the water quality was always reducing drastically fast and this affected the fishes, because they were now eating to survive and not to grow.

On the other hand, the fish population in pond 3; which to me had the best stocking density, where responding to feed and converting the food to more flesh and weight.

From observering my client and his stock, I understood that stocking density played a key role in the growth, survival and profit index of catfish aquaculture.

So, you may ask, how can I calculate the stocking density of my fishpond?

The answer to that quation, is a little tricky because many factors come into play when you wish to calculate your stocking density. Factors like pond type; concrete, earthen, or wooden; and type of water management system you apply; RAS (recyclelatory aquaculture system); raceway; stagnant or static water ponds; continuous flow through system or partial flow through. Feeding regime as well comes into play when you talk about stocking density, and it is as important a variable, as the rest of the other factor I mentioned earlier.

For this article, I searched online for “how to calculate the stocking density of a fishpond", and the results that came up, did not give me the right answer I wanted.

But I found this research that was done on the African Catfish (Clarias gariepinus), which were reared at three different stocking densities in bamboo-net cages to evaluate the effects of stocking density on growth, survival rate and food conversion ratio. Three hundred (300) fish with a total weight of 1.8Kg were stocked at 25, 50 and 75 fish/ m3 cage with a mean weight of 5.6g, 5.9g and 6.3g/m3 respectively. The growth trial lasted for 150 days (May to October).

Twenty percent (20%) of the total population of the fish in each cage was weighed monthly and the bulk weights were calculated. Moralities were recorded monthly. The final mean weights at harvest time for the fish stocked at densities of 25, 50 and 75 fish/m3 cages were 828g, 774g and 693g respectively. The water Temperatures ranged between 24.50C — 32.60C, while the salinity ranged between 24 — 95ppm.

The Feed Conversion Ratio (FCR) was 4.99, 4.73, and 3.43 respectively, and cumulative survival rates were calculated as 99.84, 99.66 and 99.50% respectively.

The results same as the analogy I gave above about what I observed from a client of mine, revealed that stocking density had a significant effect on growth, and survival rates of Clarias gariepinus.

In this research, fishes held at the highest stocking density exhibited the lowest growth and survival rate. The Cages with 50fish/m3 stocking density had the best production with total final weight being 38.67Kg and with a high profit index than the others.

Now how can we apply this recommendation locally to suit our case?

To do this first we have to be able to calculate the volume of our fish tank, and then convert that volume to liters to be able to calculate the stocking density of our ponds.

The volume of a rectangle pond is: length×bridgth×height

The volume of a cube is: lenght×lenght×length or L^3

The volume of a circle pond is: base area of pond×height. Thus base are of a circle pond can be calculated with: π*r2, where π is: 3.14, and r stands for radius .i.e. the distance from the side of your pond to the center.

The volume of a pond with various irregular depths is calculated by adding the various depths together and taking the mean height and working with it.

For example, say we wanted to calculate the volume of a 1m3 pond from our formula above; we already know from our elementary class that 1meter cube is equal to 1000L, hence based on the above research that was carried out by a group of professors at amadu bello university zaria, the optimum stocking density for maximum profitability is within the range of 50 to 75 fish per 1000L.

Conclusion:

While this may not apply to many, as a pond engineer, I think this research is good and it really take care of the concerns of an average fish farmer which is to maximize their pond for maximum profitability.

This method of calculating stocking density is by far the best and easiest I have come across, and it is applicable to wooden and surface vats.

Please subscribe to our blog to get more success tips for a successful fish farming business.

Also, please leave a comment below or send us an e-mail. We will love to hear from you!