Originally Posted by Anna94
But I'm already at 17 fish in a 20 gallon. If I add 2 more lemon tetras and 3 or 4 more Celebes rainbows, that will bring me to 22 or 23 fish and I will be overstocked at that point and I'm trying to avoid that.
I agree, in proper numbers that's too many fish for the tank... I was answering your question as to the number of Lemons and Celebes.
Knowing that you can not keep this many different species in the proper numbers means that you need to decide which species you will keep (in the proper number) to prevent overstocking.
Truthfully, my own personal preference is one larger group of a single species - I think it is more natural and you witness the fish in a more comfortable setting.
Certainly there are fish that can be kept as singles or pairs and would compliment a nice single species shoal in a 20 long. Apistogramma comes to mind, you could have a single or pair of apistos plus 8-9 Cardinals.... this is just an example.
You really need to decide which species you like and keep that fish in the proper numbers - tough choices YES - prudent YES.
Good luck and happy fish keeping!