Fish a new way...Learning

I thought I had tried every way of cooking fish: steaming, boiling, grilling, broiling and microwaving. Well the other night brought me a new variation. I had two beautiful fillets of wild striped bass--skin on--gently lain in a shallow roasting pan just large enough to hold them. I put them to one side while I concentrated on the salad and potatoes.
Fortunately, I had remembered to turn on the oven to my usual 500 F. with one rack at the top and one near the bottom. I washed the salad and got the dressing ingredients ready. Unlike most people I sdon't make the dressing apart and ahed. By now, I know what it will take.
I put the baby--creamer--potatoes in another roasting pan and slicked them with olive oil. I slipped them onto the lowest shelf thinking that they would take thirty minute about twice the time needed for the fish, around three inches thick.
I put the potatoes on the bottom shelf, set the table, made apitcher of water and tossed the salad. I looked at my watch and to my horro realize I haad only left about seven minutes for the fish. When I took the potatoes out and checked the fish and, of course, it wasn't cooked. What to do? I thought that the bottom shelf was hotter. I quickly put the fish pan on it.
Miracles: the fish came out beautifullu cooked.
I wil try this on purpose another time.