Zebra Dartfish strange behavior

[Mwag]

I noticed that my zebra dartfish started doing this thing where he would sort of flick off the substrate. I read that this could be flashing but he is a heathy fish. Eats like a pig, always out and about. I did a water change last night and everything is normal. The other tank mates leave him alone. I have a pinkbar Goby paired with a pistol shrimp along with two cleaner shrimp. Tank is 55 gallons.
Ammonia: 0
Nitrite:0
Nitrate:0
pH:8.0
Temperature: 78

 

[Big G]

How long have you had the dart fish? Have you added any new "livestock" or any thing "wet" (corals, etc.) to the tank in the last 30 days or so?

 

[Mwag]

I added a zoa coral a while ago. It might’ve been over a month ago but that was the last time I added anything. I’ve had the dartfish for about 3-4 months. I quarantined him the first month I had him so he has been in DT for 2-3 months

 

[melypr1985]

Flashing or rubbing against the sand or any other object isn't normal. It's indicative of a parasite being present such as ich. If he does it only twice a year, then no big... but if he's doing it daily or even many times a day... that's not normal.

 

[Big G]

Did you QT the Zoa?

 

[Mwag]

I did not QT the zoa