Ok, on to my favorite thing in the world, shrimp! Lol
If you have a spare 10G, that would be amazing! I find it to be the perfect size for a shrimp tank.
Choosing Shrimp:
If your a beginner shrimp keeper, definitely start with shrimp in the neocaridina family. They are much easier than shrimp in the caridina family. Some very easy shrimp in the neocaridina family include red cherry shrimp, snowball shrimp, blue pearl shrimp, red rili shrimp, (a newer, absolutely STUNNING shrimp) blue velvet Neo's, and yellow shrimp. All are very easy to keep, and will breed prolifically!
Flora:
Plants are very important in a shrimp tank, they provide food for shrimp of all sizes. One of the best plants that house micro fauna for the shrimp, is moss. Java moss will do perfectly. The roots of floating plants are also great additions to any shrimp tank! You can try dwarf water lettuce, frogbit, Azolla, red root floater, and duckweed.
Fauna:
If you really want to see shrimp behave how they normally would in nature, don't add any fish to the tank. Adding fish will make the feel like they're constantly threatened. Fish will also most likely eat newborn shrimp with ease. Trust me, a thriving colony of shrimp flying everywhere never gets boring!! Especially when they frenzy over the food at feeding time
lol if you do give in to adding fish, try to add micro fish like CPD's (celestial pearl danios), and most members of the rasbora family. My favorite shrimp tank fish are chili rasboras, they truly are an amazing fish!! Definitely loaded with personality
oto's are perfectly fine with shrimp of ALL ages.
If you have any more questions at all, please feel free to PM me!! I'd be happy to help