Update: I added a "fungus clear" tank buddy (active ingredients: nitrofurazone, furazolidone, potassium dichromate) to the old tank with Astro because I figured it can't hurt.. it says it treats fungus and bacteria related conditions. I forgot I had them.

He is still swimming around like he can't get comfortable even in the established tank. Poor guy, I wish he would just chill out and eat something.