Ok, thank you. I was thinking it had to do with stress. My LFS just got a large shipment of more today, should I try to go back and get 2 more, or leave it at 3?
If a fish dies in your tank, do not add anything new to that tank for a month. This gives the tank time to settle down and recover and if it's a disease, adding new fish will simply add to the problem.
If you want more gouramis, leave them in the shop for 2 weeks before getting any so they can recover from the stress of being shipped to the shop. Find out when the shop does water changes and get some the day before they do a water change so there is less stress to the fish before you move them to your tank.
If you do get new fish, put them in a quarantine tank for a month.
Do a big water change and gravel clean your tank the day before you add new fish to your tank.
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If you post a video of the remaining fish, it might show something, and some more pictures. Put a dark picture on the tank first to try and contrast the fish and hopefully it will have slightly darker colours. But I think you just got a bad batch of fish.
How many gouramis did they have when you bought them?
How many of those gouramis does the shop still have left?
How big are the gouramis, they look pretty small?
Find out what the pH and GH of the shop tank is?
If they have a low pH, then it might have been pH shock and would explain why the shop said your pH was too high.