Zebra Otos are notoriously hard to keep alive. Zebra plecos take a little more work also. Neither fish should be purchased by someone with little to no experience.
Seriously there is about 100 different species of pleco that will have no problem fitting in a 40. Just research what you want. Some of them take a little extra TLC.
edit to say: SCL, it's normally bad form to post other peoples pictures without permission. A link to planetcatfish may have been better. I apologize if Blue gave you permission.