You might want to go with a 24" but since the UVB should be right alongside the basking bulb at the right distance of 6 to 8", then he should be able to get enough exposure while he is basking.
I just set Swordtail's timer for his bath and paused it so I could actually fill his soaking bowl up and he crawled over my phone and canceled the timer
Mirage came out of brumation on April 26. He was doing great. On May 2 he started acting funny. We just redid his tank, and he keeps going into one of his hides. He just lays there. He shows no intrest in food. HELP!