I don't know where you found information which classed all plecs as "messy, messy fish and they'll foul a Discus tank in no time." but for the most part, it's not true.Teelie said:Plecs are no good either unless you don't mind doing the extra work cleaning the water more often. Plecos are messy, messy fish and they'll foul a Discus tank in no time.
Plecs would be fine. However, I would get a plec that grows any larger than 8" or they may take a liking to the Discus and suck on its side, I have seen this happen with Royals. Take a look on Planet Catfish. For example -
Golden Nugget L177
King Tiger L066
Leopard Frog L134
Zebra Plec L046
and so the list goes on.......................