Y. sidthimunki is really the only one that stays under 3 inches and has the botine loach shape. The others are all 4 inches or up (zebras, skunks, yoyos, etc.)\
Many of the hillstream loaches are in the 3-4 inch range but will require a specialized setup.
The kuhli family tend to be somewhat longer than 3 inches, but have a small bio load for their length.