Looks like a bacterial bloom to me.
TL/DR: either do nothing and watch your fish closely, or increase oxygenation and run UV.
It’s very important to note these consume massive amounts of oxygen, which worsens when the lights go out. I’d highly recommend adding an airstone and/or skimmer as soon as possible, to increase oxygenation in a small tank. I lost 75% of my fish last time I had a large bloom during a tank transfer, presumably due to anoxic brain injury based on the fish behavior (couldn’t get them into the QT fast enough, happened overnight. Very sad situation).
UV light (green killing machine from petco works well for smaller tanks) should help in clearing the bloom over the next couple days as well.
Alternatively, you can just wait it out and it should clear on its own in a few days. I wouldn’t change your feeding habits or anything else necessarily, but watch your clowns for rapid breathing around the surface which can be early signs of hypoxia. No matter what I’d recommend an air stone or skimmer to be safe. I’ve gotten through several blooms without either, but better safe than sorry
