I have a FOWLR
and I rearranged the rock last week. Today I noticed that I have these things growing on my glass and in my sand in one spot. I have looked all over and it looks like they are hydroids. They are very small and kind of pink/brown in color. I scrapped them off of the glass with my mag float. I am reading they are very bad for corals, what about fish? I have also found what I think is a aiptasia in between some of my rock. I added some new rock about 2 weeks ago. Will any of these hurt the fish?