Who Gives A Fish Forums

My Zoanthids have been closed up for two days now. Water params are good, 0 ammonia, 0 nitrite, nitrate at 5 ppm. Tank is a 40-gallon with AI Prime lighting, running 8 hours a day. I did a 10% water change three days ago, using Red Sea Coral Pro salt. Any ideas what's messing with them?

Could be a few things. First, check your alkalinity and calcium levels. Zoas are pretty chill but they don't like swings. Also, any new fish or inverts added recently? Sometimes a crab or shrimp can bug them. What's your temp and salinity at?

Buddy wrote: ↑Wed Apr 23, 2025 7:50 am Could be a few things. First, check your alkalinity and calcium levels. Zoas are pretty chill but they don't like swings. Also, any new fish or inverts added recently? Sometimes a crab or shrimp can bug them. What's your temp and salinity at?

Agree with Buddy. Alk swings are a big culprit. Test your Mg too, low Mg can throw off everything. Also, how old are your bulbs? Older LEDs can shift spectrum and stress corals.

Yo, my Zoas did the same thing last week. Turned out my cleaner shrimp was being a total jerk and picking at them. Maybe check for hitchhikers or pests. Also, what's your flow like? Too much or too little can sketch them out.

I'd double-check your water change routine. Did you match temp and salinity exactly? Even a small difference can stress them. Also, any chance you overdosed something like iodine or trace elements? Zoas can be sensitive to that stuff.

How's your phosphate level? High phosphates can cause issues, even if nitrates are low. Also, any chance of stray voltage in the tank? I've seen weird behavior from corals when a heater or pump was leaking current.

My Zoas closed up when I moved them to a new spot. Maybe they're just adjusting to the water change. Give it another day or two.

Haha, my Zoas are drama queens too. They close up if I look at them wrong. But seriously, could be a combo of things. Did you change your carbon or filter media recently? Sometimes that pulls out stuff they like.

Thanks for the advice, everyone. I'll test alk, calcium, and Mg tonight. No new fish or inverts, but I did add a small powerhead last week. Maybe that's too much flow. I'll dial it back and see.

stevana wrote: ↑Wed Apr 23, 2025 3:47 pm Thanks for the advice, everyone. I'll test alk, calcium, and Mg tonight. No new fish or inverts, but I did add a small powerhead last week. Maybe that's too much flow. I'll dial it back and see.

Good call on the flow. Zoas like gentle, random movement. If they're getting blasted directly, they'll close up. Let us know what your tests show.