Infection of the brain and spinal cord of wild and cultured yellow perch by Myxobolus neurophilus results in disease with neurological clinical signs. Myxobolus neurophilus is a neurotropic myxozoan that appears to infect only yellow perch. Infection is diagnosed by microscopic examination of touch impressions, smears or homogenates of brain, or of histologic sections of brain and spinal cord. The developmental stages of the parasite migrate through peripheral nerves, spinal cord and brain to invade vertebral and cranial cartilage. The most significant infection of neural tissues in laboratory fishes is that caused by Pseudoloma neurophilia in zebrafish. Pseudoloma neurophilia is a microsporidium that has a pronounced tropism for neural tissues, with clusters of developmental stages including spores forming within axons of the hindbrain, spinal cord and ventral nerve roots of the zebrafish. Fish are hosts to a wide variety of microsporidia, belonging to a number of genera, several of which infect central and peripheral nervous tissues.