I'm hoping someone can help me with a question regarding the Clinostomum parasite. When I stocked HBG in march of 2009, I also put in 25 male BG, of a considerably larger size, that I transferred over from another pond. There were no visible signs of parasite infestation in the native BG, or the smaller HBG. During my limited ice fishing forays this winter, I caught 3 native BG that were absolutely covered with yellow grubs. I'm aware of the bird, snail, fish, lifecycle of Clinostomum, so I know how they got in the pond, and my fish, I just don't understand why only the BG were so infested? There's approx. 500 HBG, compared to 25 native BG in that pond. I've only caught 8 Hybrids total since the initial stocking that had any visible parasites. And even then there were just a couple grubs per fish. Nothing like the native BG, their fins, tails, and gills were full, worst cases I have ever seen. My question is this: When the cercaria leaves the snail to find a fish host, what determines a suitable candidate? Is it the first fish that comes along, or are there factors at work that may tend to make certain fish more susceptible?
