Just saw the video. The fish is definitely exceeding the normal breathing rate and in stress. It should be in a QT with extra aeration. QTs can be 'jump started' using bottled live bacteria sold at many aquarium stores and online.
Other questions posed in my previous post are needing answering. If this is a recently acquired wild caught or tank-bred fish I'd suspect either
Brooklynella hostilis (Brook) or possibly gill flukes/worms. Both of these can spread to other fishes in the aquarium and another reason to get the fish into QT as soon as possible.
Without a microscopic confirmation to determine the problem this is about all I could say.
Treatment may be too late however each condition is treated differently:
Brook: Treat with Metronidazole. It is often mixed with Focus or Agar to ingest at 0.50% by weight in food. But there is no time for this single approach. Also, getting the right amount into the fish is hard to do -- too much could be harmful -- too little is ineffective. Best is a bath or a QT treatment. Concentrated bath treatment: 25ppm concentration for 24 hours. Internal eating treatment for 3 weeks. QT treatment: Dosage is 25 mg/gal every 48 hours (or every 24 hours for severe problems) with a 25% water change before each treatment. Treat for 10-14 days.
Gill Flukes: A general 'test' for flukes is to give the fish a FW dip. Even if it is gill flukes a FW dip may provide a temporary relief. After the
Freshwater Dip Procedure, check the dip water carefully. If you see sesame seed shaped things, then the fish had flukes. If you donāt see anything with the unaided eye, there still may flukes/worms in the dip water. Gill Flukes are not visible to the unaided eye. Do you have a microscope or access to one? If so, check the dip water (surface, mid-area, and bottom) under a microscope. You may see blobs/spots or shapes like
seen in this post. This also confirms the fish has flukes/worms. If you donāt have a microscope or access to one, no problem. Just assume the fish has gill flukes. The dip is a temporary relief for the fish. If worms are found or suspected, then treatment with Praziquantel is needed, as found in the
Praziquantel Treatment Post.