Recirculating Aquaculture System (RAS) Fundamentals (Part 1 of 6)
Authored by Gary Hall and based on his personal (ongoing) tilapia farming journey
There are several fundamentals that need to be followed in every aspect of life, aquaculture is no exception. The insights gained and shared in this series of articles are not from a PhD or training courses. Instead it comes from trial and error by building and perfecting systems to the point that “failed” or rather underachieving systems start to return a profit. These fundamentals are aimed at clean water, low waste RAS systems, not biofloc systems.
When a RAS system is designed it should have two key considerations as important focus points. The first being what is the desired tonnage or monetary value expected per year? The second being how much funding is available to accomplish this task?
Nile Tilapia in RSA is seen as a commercial fish and most farmers want a commercial farm. This commercial endeavour will only be successful if the fish grow and breed at a specific rate and achieves a target weight in a set period. If these targets are not met, the commercial farm will fail financially and will not be able to run indefinitely. For the targets to be met, every aspect of the RAS system needs to be perfect or very close to perfect.
If all fundamentals are followed, the process of cleaning and aerating the system can be achieved using less energy at a cheaper cost, allowing targets to be met.
When starting a design, a simple processing design timeline should be drawn, this timeline holds all the fundamentals in place and prevents the designer from skipping steps that could compromise the effectiveness of the system. Whether the system is 10 000l or a 1 000 000l the fundamentals remain the same.
No system is perfect – there is always some sort of compromise taking place (even if it is not readily noticeable). However, one should be able to within the confines of your system, create an ideal situation for your fish to thrive.
Every potential farmer who purchases a farm from a designer should have the system checked by at least one other competent farmer/consultant. The farmer/consultant should be independent of the designer and have a proven track record with a respected name among their peers. Preferably with a commercial farm that is producing the claimed tonnage every month that their system is supposed to produce.
A Flagging health system has been developed by a local veterinarian. Farms with a designer who achieves the best system and health flags, would be safer to buy from rather than a design with no checks in place. Within TAASA there are many farmers willing to chat to you. They will give you guidance on the above criteria – we all want to see new farmers succeed.
In the series of articles that follow I will be looking at the factors below and their impact on a RAS. I will share some of my thoughts on these factors and their importance:
In the next part of this article I will be dealing with solid removal, suspended solids and solid removal.