What is an electrofisher?

What is an electrofisher?

An electrofisher is an electronic device that allows people to catch large quantities of fish quickly with some practice. The principle of the electrofisher is based on the fact that when direct electric current flows through water, fish experience a so-called anode reaction (galvanotaxis), under which they move from negative electrodes to positive electrodes. The most interesting aspect is that the larger the fish, the more willingly it moves towards the net.

The diagram below illustrates the behavior of fish under the influence of electric current.

The anode reaction of fish (moving towards the anode) can be explained by the fact that fish can sense the direction of ion movement and orient themselves with their heads towards the ion stream. Under the influence of an electric field, the muscles of the fish contract, causing them to rise automatically. In reality, if the voltage around the anode is higher than a critical value, the fish cannot reach the anode.

In this case, the fish enters a state of nervous shock, either floating to the surface or sinking to the bottom. To prevent this, we can adjust the voltage based on the distance between the cathode and anode.However, this presents certain technical difficulties. Trying to maintain the optimal electric field while increasing the distance between electrodes enlarges the dangerous zone for fish. Moreover, the parameters of the applied electric field largely depend on the conductivity of the water (salinity), temperature, electrode surface, and power source. There are many types of fish, differing in size.

Research has shown that this phenomenon only occurs with direct current or pulse current. Direct current appears most effective but is somewhat limited to low-conductivity freshwaters. In saltier waters, using direct current would require large power supplies. As a result, we commonly use pulse current in most cases. Pulse current is more efficient at using smaller amounts of energy to power the electrofisher.

The main purpose of electrofishing is to catch fish for reproduction, but it can also be used for commercial fishing. Equipped with such a device, a fisherman can press a control button, dip the electrodes, and easily capture the “hypnotized” fish. During fishing, different sizes of fish swim up; small fish, after recovering from nervous shock, swim away randomly within seconds, while larger ones are selected by the fisherman.

When sufficient electric current flows through water, fish move from the negative to the positive electrode. This reaction is called the anode reaction. The key to electrofishing is that the electric current must be direct current. However, to generate sufficient direct current to cover enough water areas, no battery would be large enough. Therefore, we use pulse current. It is important to understand that each type of fish requires specific pulse parameters. Various factors such as weather, season, properties of the water, and the biological state of the fish all influence the effectiveness of electrofishing. Today, electrofishing is a modern fishing technique. The electrofisher needs to meet many conditions and requirements to effectively catch fish, as outlined below.

Without delving too much into theory, here are the criteria an electrofisher should meet for effective fishing:

1. The electrofisher should be as powerful as possible for the given battery (accumulator), allowing for an expanded fishing zone. However, it should be ensured that the fish can swim freely to the net under optimal fishing conditions without getting hurt, and if necessary, can be released (small fish, fry).

2. It is important to ensure the flow of electric current (Amperes) in the water, rather than voltage (Volts).

3. The electrode surface should be as large as reasonably possible to increase the current flow and allow easy operation. The cathode should be a piece of flexible copper wire, 1.5-2 meters long and about 2 mm thick.

4. The intensity of pulses should be minimal while providing adequate power to the water within the given time.

5. Pulse frequency should be adjustable from 5 to 120 Hz.

6. Pulse length should range from approximately 30 microseconds to 3 milliseconds. At lower frequencies, the pulse width (length) should be larger.

7. The electrofisher should work properly within a resistivity range of 20 to 500 ohms.

8. The battery can confidently provide current in amperes equal to its capacity in Ah (Ampere-hours).