Aquarium help

I would leave out the ottos for now. There are fairly delicate fish and probably won't be needed, at least not right away. They will clean up brown algae so if you see some of that then you can make the decision to get them. Also 2 should be fine, you don't need 3 in such a small tank.
 
Something you may want to check is your waters ph level and hardness. Test kits are fairly inexpensive and will help determine what you may need to do or what fish will be happy the way it is.
 
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