In a 2.3 gallon tank, the betta will have pretty much zero suitable tankmates. That's pretty small for a betta by itself, but that's another issue. You should not really need any cleaner crew for such a small tank, either.
you'd think... BUT i got a 6 gallon tank, plants, etc for my betta (that's what started it all) and while my betta thought the 'all you can eat sushi shrimp bar was great, he didn't love the tank... as a "you stop that and go to your room" move I put him in a 8x8x8 tank.. and he was happy as a clam (bubble nests daily, and no more sad look) ... I think he likes being in the middle of the table where i work and see/talk to him during the day (he has a nice tank)
the question becomes, how to keep everything alge free if i don't have a little cleaner for him. I have 2 betta (both hated the big scary tank even with the filter baffled), they have heaters, lights, plants, and are front and center when i work.