Romet has been around a LONG time. We used it extensively 20 years ago in the culture of Goldfish. It was available then prepared as a pellet feed and the fish took it readily. There are two things I would like to note: 1) this was fresh water, and different experiences do apply. We treated separately for ich, using formalin and malachite green in those days. We so no effect of Romet on freshwater ich. 2) the Romet we used I think was called SDMX-TMP.....which was trimethoprim, not ormetoprim. Could this make a difference? I just think that if such a common agent available in a commercial feed were effective, we would have know about it before now. Especially since the Romet feed was being used in aquaculture. But I do not recall any use in marine environments from those days.... thoughts?