He's got places to hide. It's been about five days since I brought him home. I was going to run a course of Formalin, but only dosed once because he looked stressed afterward. He is a one-inch fish in a fifteen gallon tank. I did a 66% water change today. The temp is at 75º. Aquaclear HOB filter and airstone for slightly more oxygenation. The only things in the tank are the fake plants and plastic stone statue he hides behind. Should I pack the tank with fake plants or something? Dithers? I do have some guppies. Or should I just give him some time to adjust and keep up with normal maintenance after making sure it's seeded and cycled properly? I didn't check parameters today, but he doesn't look stressed by toxins. His breathing is slow and his fins are held high. He just won't come out, that's all.