Pecan will be fine for the smoke. I do hot smoked catfish at 250-300° until the fish flakes easily. For catfish, you may be OK with it on the grates, but I highly recommend that you use a fish basket for the catfish and DEFINITELY for the crappie. Both will easily fall to pieces if you aren’t careful.
Another way I’ve done it without the baskets is to make a small tray out of heavy aluminum foil. Lay the fillet into the tray, add some seasonings and maybe a pat of butter to the tray and then smoke.
As a “rub” for the fish, I always slather them with a thin layer of EVOO or spray with Pam, and then add my seasoning of choice. Wife likes it with lemon pepper, I like it with Tony’s.
just smoked fish for the first time. I also used a curing brine for almost a day. Then I pulled the fish out and rinsed it off and set it on the smoker grate to dry out a bit. then placed it in my MES with the AMNPS full of apple pellets and smoked at 100* for about an hour then kicked it up to 130* another hour to two and finally up to 165* until it looked mostly dry. It was yummy! Oh, and it was catfish and redfish.