Flatworm infestation—need suggestions

TankYouVeryMuch · Mar 22, 2026

When I say I have an infestation of flatworms, I am not exaggerating.

This is an overhead view looking down into the 25g tank. I hoped the population would spike and then crash, but that’s not what has happened. They’re now smothering corals. I have tried siphoning them out but there are so many that it’s nearly impossible. I have flatworm exit available but gather that it’s likely to just nuke the tank and kill everything due to the sheer number of them releasing toxins at once when they die.

I gather my best bet might be to transfer the fish to a temporary tank, treat the rocks in a bucket with Bayer insecticide treatment, and then treat the tank with flatworm exit and do a big water change, but I’m not convinced it’s going to work. Open to suggestions.

GoReefin · Mar 22, 2026

If this strain is resistant to flatworm exit:
Fresh water dip everything, take a good brush and scrape all the coral bases for eggs move all livestock to a different tank. You can then start hyposalinity which will kill all the worms. Once dead do a good water change and bring your salinity back up then transfer everything back over and get yourself a 6 line wrasse or yellow coris wrasse to prevent them from coming back.

TankYouVeryMuch · Mar 22, 2026

GoReefin said:
If this strain is resistant to flatworm exit:
Fresh water dip everything, take a good brush and scrape all the coral bases for eggs move all livestock to a different tank. You can then start hyposalinity which will kill all the worms. Once dead transfer everything back over and get yourself a 6 line wrasse or yellow coris wrasse to prevent them from coming back.

Thanks for the suggestion. How hypo are we talking?