The bristlenose plecos will be fine in the 46. You can also have the cories too.The plecos will only reach around five inches each and they will take care of the algae in the tank. For this reason you should probably wait on the plecos until there is sufficient algae present in the tank which should take about eight weeks. The cories will eat any leftover food that the other fish do not eat. They are a great clean up crew. Depending on the ones that you get will depend on how many to get. I would suggest that you get at least three cories since they are very social little creatures and perfer to be in groups. The panda cories stay small and are really cute if you are looking for a suggestion.
Marinemom