Living plants are fine, and a couple of shrimp are cheap, which is good, because you don't know if the betta will handle them well. But the more plants and hiding places for the shrimp, the better. Some flat rocks proped up so they have maybe a half inch under them for the shrimp to hide works really well, and heavy carpeting plants give them a good place to hide.
And the point of the 5.5 is to make the betta happy. Remember he needs room, too. Betta are often kept in very very tiny tanks, but they suffer for it. It would be like you or I living in a closet. You've given him a nice big apartment to roam around in and I'm sure he would be thankful for it if he could talk.
Bettabettabetta [~] Corrin [~] Mega [~] Rinji [~] Red Robin [~] Jr. [~] Billy [~] Opti
Tidbit [~] Princess [~] Little [~] Spazz [~] Rosie [~] Sakura [~] Cocoa [~] Pylia
So many fish, so little sig room :)
Miko - forever kitten [~] Cain & Tyrael - twin cats [~] Sadie - RN Pitbull; Proud new mother!! 1-21-13
Gwen - Perfect Daughter!