I have these colonial hydroids. They seem to not harm other corals. They harm me. I was getting arm blistering here and there. Thought I was getting a salt allergy. I hate to wear gloves. One of our local reef members told me what these colonial hydroids were. I spent last night scraping them off the rocks. This morning after a sleepless night My arm is covered in burning welts, hands too. Once you scrap these they spread. They have already spread around the tank. Do not seem to harm the fish, they seemed to not care. I did not see a reaction from fish or clams. This tank is 8 years old and has five clams in it, live fiji rock, lots of baby rock anemones that are beautiful pinks and red, Sps, duncans, hammers, etc. . I am not going to kill the tank. I can not cut down feeding for we have a Mandarin fish that needs to be fed gut-loaded brine shrimp which hydroids love. This is part of reefing that really stinks. I am going to have to wear long gloves all the way up the shoulders and keep the hydroids scraped down, water changed, and hope for the best. I did not find any on the back of the rocks. They are all out front in the light where one can scrape. I am also going to be covering some of the colonies with epoxy. This might be something some people would quit over. Once they are in a system they are in. You have to start over with everything being nuked from skimmer to refugium, to everything. This after I just go Dinos under control in two tanks. I hate these things. I thought they were pretty. I thought they were feather duster-type corals. I was even thinking of moving some to my 125-gallon tank because they look pretty under blue light. Do not make my mistake. See these kill these before they spread. I let my spread.
