Hydroids on New Frags

atlantean · Jan 31, 2021

Just added a Goniopora and hammer coral frags to my tank last night. Today I noticed some small hydroids on them. They're a little small to get a picture of, so I included a picture of the type they resemble. I think I could remove the Goniopora from the plug and toss it but the hammer would be more difficult to salvage while removing the hydroids. Would you toss the hammer coral or not worry about them?

Dkmoo · Jan 31, 2021

how old is tank? what else are in there?

my experience with these branching hydroid is that they can "come and go" in monthly cycles but once they are in your tank, it's going to be impossible to get rid of them b/c the typical CUCs do not touch them. They spread quickly and can sting corals if they spread too much to a coral. They feed on dissolved organics instead of nitrate/phosphate.

My tank is 4 years old, very mature and stable. These would pop up whenever i feed my corals too much (just went thru another round last month when my Vibrant treatment caused too much dissolved organics). My other filter feeders (feather dusters, sponges, vermetids) would catch up and out compete the nutrient so they'd then go away on their own after a few weeks. This is probably one of the only ways to keep them in check once they take a hold in your tank - they reach a natural equilibrium with the rest of your tank.

In young tanks it will be harder to control this way b/c you won't have the necessary bio diversity in your filter feeder population. In this case really the only way is to either starve them out, use aggressive filtration to remove desolved organics, or a "hit or miss" scourch earth medicine that will also kill off your biodiversity (forgot the name, google "hydroid treatment" and it's the only name that pops up)

Depending on where you are in the above, might be better to just toss the whole thing out if you can't carefully and tweeze them out of the frag/hammer. a quick search on these forums and you'll see a lot of pain stories on how to deal with hydroids - the worse ones will be of the "colonial hydroid" variety. Your branching hydroids arent as bad, but I think most would find them still a headache to deal with due to its fast spread rate and a lack of natural counters in our tank.

Anthony Scholfield · Jan 31, 2021

I also have them come and go. I dont find them to be a major problem though. I have experienced instances where the hydroids bothered some corals they were growing on but i would remove them by scrapping, cutting or tweezing.

In your situation i would just remove them to the best of your ability, watch, and move forward. It seems a shame to ditch a perfectly fine coral because of a few simple hydroids. That’s just me though. :)

atlantean · Jan 31, 2021

There's also some vermetids on the skeleton, which I tried to tweeze off since I don't have any in the tank at the moment.

The tank is only a month old but has quite a bit of biodiversity inherited from KP Aquatics live rock. Still, I imagine fighting them will be an issue. I just cut the Goniopora off the plug, so it has at least been salvaged.

Right now I'm thinking of cutting the healthiest looking hammer coral head just below the tissue and then gluing it on a small rock. I think the hydroids are too small to catch all of them so I think the least amount of exposed skeleton I retain the better.

I wasn't totally crazy about having a hammer coral but wanted a more affordable LPS to test the waters before splurging on any of my favorites. Feel guilty about potentially tossing a coral though. What do you think?