The excised spherical metacercaria is 2.7–4.9 mm long.[2] Generally, only one is found per fish.[3]
Life cycle
Some species of Galactosomum cause infected fish to swim closer to the surface and colorfully flash their underbellies.[4] In fish, symptoms can be similar to those of whirling disease caused by the unrelated parasite Myxobolus cerebralis.[3]Gastropods hosting select species suffer from sensory impairment due to infestation. This makes these prey animals more likely to be consumed by aquatic birds, providing a host for the parasite to reach the mature stage of its life cycle. Galactosomum cannot survive in human hosts.[4]
^Kamegai, S.; N. Yasunaga; S. Ogawa; S. Yasumoto (1982). "Galactosomum sp. from intestine of Larus carassirostris from Nagasaki, Japan". Jpn. J. Parasit. (in Japanese): 31.