Sorry so late to respond. If you don't get immediate answers try posting in another related forum. In the Aroids discussion there are several topics on Caladiums. Try posting there with the word 'Caladium' in the title.

I'm not sure what those bugs are, but I've had some bugs that looked exactly like that on my Mound Lily Yucca plants outdoors in the ground over the years. I just sprayed them with horticultural oil twice in 1 month and they disappeared. I've bought horticultural oil for indoor plants too and it worked but needed repeated applications. Every 2 weeks. Hopefully all is well with those Caladiums now.

As for the fungus, my nove response is to maybe try one of the more expensive fungicides. I've only used 2 over the years and the less expensive one was less effective. The cheaper one was also organic. Sunshine filtered through a window screen killed some white furry fungus that grew on the soil of one of my Caladiums. When I set it outdoors some days in a slight breeze in dappled sunlight even more the the fungus disappeared. Air circulation and some sunlight can help minimize fungus.

Is that a Fannie Munson Caladium?

Are they aphids? Sorry, but none are in focus. I always associate aphids with little white cast-off skins, which I think I see among the darker insects. Aphids come in a wide assortment of colors, but mostly have the same shape and size. You can look them up and compare with what you have.

I also cannot see anything of a fungus that might pose a problem. Some potting soil fungi are not the kind that pose a problem for plants at all and don't respond to fungicides.

Since it is never a good idea to dose with pesticides (fungicides are a type of pesticide) without knowing exactly what the problem is, maybe you can try some improved images so we can take another stab at it.

Old post, but relevant. Perhaps someone can ID this pest currently on my caladium via this photo ... It’s the best I can do with my cell phone camera.

To the naked eye, they appear as black dots on the stalks. Enlarged, they appear to be mites in various stages.

I removed what I could feel as grainy under running water. I followed up by spraying the plants and soil with neem and liquid castile. When I spotted another moving black dot, I sprayed everything again with isopropyl alcohol. Please help!!! Thanks.