I could be wrong, however I believe the clown likely doesn’t have brook. My main concern is the elevated breathing and stringy feces. Before I use multiple medications and potentially stress him out further, I need to get him to eat.I can’t download the video. Difficult breathing is definitely concerning. It’s good you tested ammonia and its zero as new QT systems may not have adequate denitrification. If it is brooklynella you still have options. A formalin/ malachite green dip can knock down the immediate bioload of the pathogen but then will need to continue treating the tank ( I am assuming you don’t have another sterile QT tank.) understanding the microbiology helps as there is a lot of treatment options on the market. Velvet, ich, uronema are protozoan infections . Not all antibiotics are effective. Using human medicine as a comparison: chloroquine was developed to treat malaria (a protozoan infection) it is therefore logical to presume that its effective against brooklynella (most references say it is). Metronidazole (aka flagyl) is an antibacterial but is also effective against trichomonas infections in people (a protozoan infection) so it might be effective against velvet. I personally like chloroquine. You can dose the tank directly (be very precise in your measurements) or use impregnated reef caviar. The later is tough to find but the direct dosing form is likely available at a good local fish store