Aquaculture
Lack of oxygen can cause massive harm to fish, reducing appetite, compromising growth and well-being, and ultimately resulting in death. The following chart visualises the impact of oxygen saturation on the growth rate, mortality and food conversion ratio (FCR) of salmon for instance.
Negative impact of low oxygen levels
Saturation levels can drop to 85% with no negative effect on fish well-being, yet once it falls to 75%, the fish reduce their metabolism. Below that level, appetite decreases further, at 60% the fish start to die. Massive mortality results if oxygen saturation keeps falling to reach 40% or even 30%.
According to A Fish Farmer’s Guide to understanding water quality by LaDon Swann (Purdue University), “dissolved oxygen is by far the most important chemical parameter in aquaculture. Low-dissolved oxygen levels are responsible for more fish kills, either directly or indirectly, than all other problems combined. Like humans, fish require oxygen for respiration. The amount of oxygen consumed by the fish is a function of its size, feeding rate, activity level and temperature. Small fish consume more oxygen than do large fish because of their higher metabolic rate.”
Improving farming efficiency through oxygenation
Maintaining oxygen saturation levels above 90% is the key to efficient aquaculture. Experience has shown that efficient oxygen dissolution and distribution systems have a positive impact on a number of key parameters. These are outlined in the following.
- Improve feed conversion ratio (FCR) for feed cost savings
A reduction in the FCR from 1.5 to 1.0 can lower production costs by up to 20% - Higher specific growth rate (SGR) for increased profitability
Increase fish growth rates even on higher stocking densities - Promotion of animal welfare in accordance with active corporate responsibility,
compliance with regulatory requirements and consumer and retail demands - Lower fish stress and mortality