Multiple Fish Flashing Suddenly - Cause Unknown

cryingrn · 2026-08-09T00:25:33-0400

Today I've had some sudden issues pop up in my reef tank that Im having trouble explaining. It started with my adorned wrasse, who exited the sand bed at her normal time this morning and was flashing/yawning excessively for the first 10 minutes or so. I chalked this up to her dislodging sand grains after waking up, since it was really only for that initial period of time and she spent the rest of the day hunting and cruising as normal.

Then my yellow tang started acting up. He would dart around and flash, and spent the later afternoon hiding in the liverock which was unusual for him. He doesnt seem to be directing this at anyone and is the only tang in my tank.

Around the same time, my juvenile goldflake angelfish decided to hide in the rock separately from the yellow tang. This is, again, out of character behavior but given that he is normally attached by the hip to my tang and my tang was acting weird, I figured this was just an extension of this behavior. I was able to lure the goldflake out briefly with food.

Then as soon as my lights went out, my chalk basslet flashed 3x in a row against the rocks. After not noticing any odd behaviors from my fish to all of this unusualness, I was officially worried. I tried pulling one of the symptomatic fish for a diagnostic fw dip, but can presently only grab one of my clownfish without taking out rocks. I took out my male occellaris and did a fw dip, but nothing came off (I didnt realize at the time that not all flukes are visible with the naked eye/receptive to a fw dip so I didnt take a sample to look under a microscope). Again though, the clownfish are not currently displaying any unusual behaviors.

Ammonia and nitrites are 0ppm.
Nitrates are 13.7
Temp has been stable at 77.6-77.8°F all day

Now, for context, Im still not able to 100% rule out water quality issues. Im currently battling dinoflagellates and put in UV sterilizers yesterday to combat them. I recently did a tank move to this 180g about a week ago and it destabilized everything. My corals all still have good PE though and my anemones seem relatively happy, so Im not really sure. I was also cleaning today around the tank. I mopped my floors with fabuloso and I did (carefully) use febreeze on my rug and furniture but was very mindful to minimize aerosol particles from going up in the air. I also cant rule out that maybe, after cleaning, if I stuck my hand in the tank without thinking and maybe had chemicals on my hand (but I dont know that I did I just cant rule out that I didnt).

So ultimately Im at a bit of a loss. Here's a video of my yellow tang doing some of the weird charging behaviors (no other tang in the tank and I dont have any aggression at all currently. I dont even think there was even anyone near him). Also a close-up of his gills bc I cant tell if they look irritated or not

I am still trying to capture a symptomatic fish for a fw dip just to more confidently rule-out flukes however

MegabiteOG · 2026-08-09T00:46:35-0400

Did you happen to be wearing a bright orange shirt? My fish freak out if I get near the tank with one. Doubtful, but figured I’d ask.

cryingrn · 2026-08-09T00:47:29-0400

MegabiteOG said:
Did you happen to be wearing a bright orange shirt? My fish freak out if I get near the tank with one. Doubtful, but figured I’d ask.

Man I wish! No it was skin colored, and these were behaviors that were happening without me being immediately present

MegabiteOG · 2026-08-09T00:54:46-0400

With just moving everything over, it can be so many things. Hopefully someone can give you advice, you figure it out, or it works itself out. I’d throw in a bag a GAC in case there are some toxins from the Dinos and move.

cryingrn · 2026-08-09T01:00:14-0400

MegabiteOG said:
With just moving everything over, it can be so many things. Hopefully someone can give you advice, you figure it out, or it works itself out. I’d throw in a bag a GAC in case there are some toxins from the Dinos and move.

Thank you. That's the frustrating thing. Maybe its flukes, but the clownfish came back with a negative fw dip and the yellow tang (who is currently the worst offender) doesnt seem like his gills are that irritated. Im thinking logically its dinos and the wq issues that come with that, but dont know if its worth it to dose prazipro for the sake of it or if the side effects would be too great atp (especially for a tank that essentially was completely destabilized recently).

I did add in a bag of the blue chemi pure yesterday, so hopefully that will help

305 · 2026-08-09T01:25:10-0400

cryingrn said:
Today I've had some sudden issues pop up in my reef tank that Im having trouble explaining. It started with my adorned wrasse, who exited the sand bed at her normal time this morning and was flashing/yawning excessively for the first 10 minutes or so. I chalked this up to her dislodging sand grains after waking up, since it was really only for that initial period of time and she spent the rest of the day hunting and cruising as normal.

Then my yellow tang started acting up. He would dart around and flash, and spent the later afternoon hiding in the liverock which was unusual for him. He doesnt seem to be directing this at anyone and is the only tang in my tank.

Around the same time, my juvenile goldflake angelfish decided to hide in the rock separately from the yellow tang. This is, again, out of character behavior but given that he is normally attached by the hip to my tang and my tang was acting weird, I figured this was just an extension of this behavior. I was able to lure the goldflake out briefly with food.

Then as soon as my lights went out, my chalk basslet flashed 3x in a row against the rocks. After not noticing any odd behaviors from my fish to all of this unusualness, I was officially worried. I tried pulling one of the symptomatic fish for a diagnostic fw dip, but can presently only grab one of my clownfish without taking out rocks. I took out my male occellaris and did a fw dip, but nothing came off (I didnt realize at the time that not all flukes are visible with the naked eye/receptive to a fw dip so I didnt take a sample to look under a microscope). Again though, the clownfish are not currently displaying any unusual behaviors.

Ammonia and nitrites are 0ppm.
Nitrates are 13.7
Temp has been stable at 77.6-77.8°F all day

Now, for context, Im still not able to 100% rule out water quality issues. Im currently battling dinoflagellates and put in UV sterilizers yesterday to combat them. I recently did a tank move to this 180g about a week ago and it destabilized everything. My corals all still have good PE though and my anemones seem relatively happy, so Im not really sure. I was also cleaning today around the tank. I mopped my floors with fabuloso and I did (carefully) use febreeze on my rug and furniture but was very mindful to minimize aerosol particles from going up in the air. I also cant rule out that maybe, after cleaning, if I stuck my hand in the tank without thinking and maybe had chemicals on my hand (but I dont know that I did I just cant rule out that I didnt).

So ultimately Im at a bit of a loss. Here's a video of my yellow tang doing some of the weird charging behaviors (no other tang in the tank and I dont have any aggression at all currently. I dont even think there was even anyone near him). Also a close-up of his gills bc I cant tell if they look irritated or not

I am still trying to capture a symptomatic fish for a fw dip just to more confidently rule-out flukes however

I’d check ammonia and stray voltage…
Especially since u did a tank transfer ammonia-wise

305 · 2026-08-09T01:27:34-0400

Also, anytime Dino’s come up… my goto is iron!
The last thing I’d do is dirty the water cuz I’ll just keep feeding em.
Watch reefbums video labeled Dino’s with Jake Adam’s .. they give u the low down on the iron