Myxozoa are microscopic fish parasites whose spread can have a devastating effect on fish stocks in the wild, but especially in aquaculture. In addition, no legalized treatment of this disease is currently available. The parallel process of direct control of infection with parasiticides and simultaneous improvement of the host immune system, so-called immunomodulation, is a very effective approach to fighting this disease. However, a fully functional system for testing substances with parasiticide or immunostimulating properties is necessary for that purpose. The in vitro model with a focus on the blood stage is the key one for testing because most species of myxozoan dwell for at least a short time in their blood before attacking the target’s organs. For immunostimulant testing, companies engaged in fish farming, nutrition for artificially reared fish and aquaculture in general, require an in vivo diagnostic system and the evelopment of such a test model is a response to that need.
