After an aquaculture project is started, one of the first things that farmers quickly realize is that they want to know more about their systems. The old saying goes that knowledge is power; and in aquaculture that could not be more true. Too often we hear from someone that is experiencing a lack of feeding response or having fish die off due to unknown causes. When diagnosing the system’s issues, we quickly learn that there was no monitoring of oxygen concentrations, ammonia levels, or any other critical parameters in the system. Unfortunately, these problems do not typically manifest themselves until late in the production cycle and if left unchecked can cause critical system failures.
The good news for us is that there are quick, easy, and inexpensive options that can help farmers monitor their system health and quickly diagnose problems, allowing them to react and potentially save their stocks of fish. The first line of defense comes in the form of a handheld meter. Typically these units are small, waterproof devices with a digital screen, small control panel, and a sensor probe. The most common (and most essential type of probe for aquaculturists) is dissolved oxygen. This probe measures the amount of oxygen in the water. Most species prefer this number to remain above 5 mg/L, but cool-water species like trout and salmon require even higher numbers. Checking dissolved oxygen levels regularly lets the farmer identify when the system is becoming strained due to the growing biomass. If dissolved oxygen levels are to drop to a critical point, the farmer should increase aeration or add supplemental oxygen to bring dissolved oxygen levels back to normal.
The two most common types of dissolved oxygen meters are optical (follow this link) and galvanic (follow this link). We always recommend optical probes if possible, as their reading is more accurate and their maintenance requirements are far lower than galvanic probes. Other handheld meters can measure even more parameters (with some models reading oxygen, pH, salinity, turbidity, and more), all in one easy to use package. We recommend that farmers sample their water using a handheld meter at least twice daily and log all water quality parameters at each reading. When a parameter is different than the norm, it is easy to tell that something needs to be fixed.
This is the first in a series of blogs called Aquaculture Insights. Check back each week for tips and suggestions to help your aquaculture system thrive!