In the study, 53 eels with a live weight of 700 to 800 g were restrained and equipped with EEG and ECG electrodes before stunning. The eels were mechanically stunned by a captive needle pistol using a shooting pressure of 8 bar and an air injection of 3 bar during 1.5 s. The behaviour was observed during and after stunning. Indices for the immediate induction of unconsciousness and insensitivity were the appearance of theta and delta waves tending to an iso-electric line, i.e. no brain activity. The duration of these waves averaged 11±8 s (n=32) on the EEG. Another nine animals showed directly after stunning no brain activity. Due to severe clonic cramps five animals were stunned twice. The ECG showed fluttering of the heart configuration immediately after stunning in all eels. It was concluded that within a confidence level of 95%, taking into account the number of animals with a reliable EEG (n=42), at least 93% of the eels were effectively stunned by a correctly positioned captive needle pistol. It was easy to stun eels with a captive needle pistol using air pressure; however, more research is needed for the development of a restraining and stunning device suitable for use in practice.