is it possible to keep a pleco with a African clawed frog? the pleco is around 9 inches long and the frog is around 3 inches long. the tank i want to put them in is 20 gallons (i think).
The only Plecos commonly seen for sale that would be appropriate for that tank are Bristlenose Plecos, Ancistrus spp, and Clown Pleco, AKA L-104. 9" long sounds like a Common Pleco, he's gonna need something in the 90 gallon range.
The frog will eat any fish that fits in its mouth, and will be eaten by any fish whose mouth it fits into, otherwise it would probably get along with almost anything.