Many of the fish suggested will get too big for the tank. Sallvini and nics are awful suggestions because they can get 8-10in. Plus salvini would rip eachother apart in this small of a tank. Because of the footprint you have you are limited to fish in the 4-6" range and 6in may be pushing it. 24" does not leave much room for a female to escape a male so you will end up with problems. I would look for fish that stay around 4". I have never kept neets but I have read they are highly aggressive. I would not keep them in this tank. If I had your tank I would look into Archocentrus nanoluteus. They stay small and are pretty hard to find. That or HRP for they stay very small as well. Add some swordtail dither fish and you have yourself a little CA biotope going.