A virus causing a vacuolating encephalopathy and retinopathy in juvenile sea bass, Dicentrarchus labrax, was isolated from brain tissue in a fish cell line (SSN-1) derived from striped snakehead, Channa striatus. The isometric, non-enveloped, 30 nm diameter virus particles were resistant to pH 2–9 and heating at 56 °C for 30 min. Infectious particles had a buoyant density of approximately 1.31 g/cm3 in CsCl. Two structural polypeptides of molecular mass 40 and 42 kDa were identified and the ssRNA consisted of two fragments of molecular mass 1.10 and 0.51 × 106 Da. From these characteristics the virus was identified as a nodavirus. Due to the broad range of susceptible fish hosts and the consistent neuropathology of the disease condition, the generic term piscine neuropathy nodavirus (PNN) is proposed for this infectious agent.