Myxobolus insidiosus forms cysts in the muscle tissues of fish. The cysts are small and even heavily infected fish do not appear to be adversely affected. This parasite is easily confused with the more recently described Myxobolus fryeri; which is specific to nerves within the skeletal muscle. Spores of both parasites have similar size and shape; and both can co-occur in the same fish. Although the life cycle of the parasite is still unverified it probably involves a tubificid worm as an intermediate host.