You have to know that every system is unique and different and individuals’ environmental conditions can vary and differ a lot. Since we cannot really change reality and the fact that systems differ from each other, there have to be common guidelines that will work well for most people. Our suggestion is that you stock around twenty to twenty-five fish for every five hundred liters of growbed media within your system. This sample assumes that you have growbeds that are twenty-five to thirty centimeters deep.
But ultimately the number of fish you can keep safe within your Aquaponic system will have to depend on several factors like pumping rates, fish species, feed rates, water flows, water temperature, a number of plants oxygen levels among others. So assuming that you are planning to make a simple system like the sample system we presented in this manual that is made from a single IBC that is cut into two divisions to make the fish tank and the growbed. The growbed contains two hundred fifty liters of media which are perfect to safely house ten to twelve fish. This size allows fish to grow from a fingerling to a plate size of around four hundred to five hundred grams. If you double the size of the growbed then you can enjoy twice the amount of fish so you can house around twenty to twenty-five fish within your Aquaponic system.
We have discovered through our series of experimentations that you can actually grow plenty of plants even with a moderately lightly stocked system. The nice thing about having a lightly stocked system is that it is more durable if ever things could go wrong. To get your fish home you need to discuss this with your fish supplier. Transporting fish often relies on the size of your fish, the distance you are going to have them travel as well as the amount of time needed for the entire duration of transit.
More often than not, fish suppliers bag tiny fingerlings in clear plastic bags but ensuring that they have incorporated oxygen into the bag for the fish. Doing so allows fish to be transported for a long period of time with very minimal chances of losses. There will be times where you will be asked to take an esky to the fish supplier. This is okay so long as you bring with you a battery aerator to supply your fish with air during the trip.
When feeding your fish we usually suggest that you utilize a quality aquaculture pellet. You can also supplement it with other feeds likes black more solid fly larvae, maggots and worms and other types of alternative feed. But it’s always a great idea to have the basis of a pellet feed available as a fundamental component of your fish’s diet. There are people who seldom ask about keeping a system in a totally closed loop, this means producing all the feed you could ever need within the system as well as from system scraps and rubbish. This can work to a small extent but you should also have an external input into your system if you are eliminating nutrient from your system in the form of food.
So the question now is how much should you feed your fish? Well, there is no limit you can feed them with as much food as they want. If your system is already mature then our suggestion is you feed your fish frequently, feed them with as much food as they want within a few minutes. If there are any food left uneaten you should remove it from the system right away before it settles to the bottom and rot since this consumes oxygen from the water while simultaneously increases the water’s level of ammonia.
So let’s say you want to generate more fish in your system but you are torn since you can no longer increase the size of your growbed, what should you do? If you want to have more fish but you can’t do anything to increase your growbed’s size then you should find a way to remove the solids from your system. Doing so can help lower the nutrient levels of yours. This specific aspect of Aquaponics is actually a contestable topic and often falls on debatable ground that is why it is really up to the person and wants they desire from their system.
If you want to remove large particulates from your systems like fish manure or uneaten food you can have the option of installing a form of solids removal like a settling tank or a swirl separator before these particulates will go straight into your growbed. But you will be required to regularly empty the solids and remove them in some way but we suggest you dispose them into your garden or into a worm farm.
We personally suggest leaving all the solids within the system because it simplifies the system while still allowing enough levels of fish production. It also ensures that your costly fish feed will be put to good use as it helps grow the plants in your Aquaponics system. (Click here to learn about Why You Need To Have A Backup System)