Are those starfish real dried starfish? Or are they fake tank decor? Not asking for aesthetic reasons, wondering whether you have real marine decor like shells and dried starfish, which perhaps could be affecting the water chemistry... Have you added anything new to the tank in recent months?
Along with the youtube video (actually being able to see the way they're swimming can show a lot), if you could copy paste the template below and answer as many questions as you know, it helps people get an idea of what may be happening in your tank
What Others Need to Know to Help You
When posting a request for help can you please include the following info
1. Water parameters. (ammonia, nitrate, nitrite, PH, temp', Hardness etc)
2. A full description of the fishes symptoms.
3. How often you do water changes and how much.
4. Any chemicals and treatments you add to the water.
5. What tank mates are in the tank.
6. Tank size.
7. Finally Have you recently added any new fish?
You may cut and paste the template below and submit in your post:
Request Help
Tank size:
tank age:
pH:
ammonia:
nitrite:
nitrate:
kH:
gH:
tank temp:
Fish Symptoms (include full description including lesion, color, location, fish behavior):
Volume and Frequency of water changes:
Chemical Additives or Media in your tank:
Tank inhabitants:
Recent additions to your tank (living or decoration):
Exposure to chemicals:
Digital photo (include if possible):