Davo86
Cichlids, Catfish and Oddballs
6 x 2inch silver dollars
1 x 6-8 inch common plec
1 x 4-5 inch oscar
1 x 3-5 inch ornate birchir
1 x 3-5 inch aligator gar
You really don't want an alligator gar, these get to about 8-9 foot in the wild and easily a good 3-4 in captivity
Even a Florida or spotted gar would get to 2-3 feet in captivity.
If it was me I would go for 3-4 Hujeta Gars (Ctenolucius hujeta) or 3-4 Needlenose Gar (Xenentodon cancila)
I would also try to get bigger SDs if possible, just in case something does try to snack on them