[Tiny Boidae]

I used to have a tank full of tetras. My favorite were the red minor serpae tetras I had. Very placid animals, beautiful, schooled nicely. I also had two other schools of rummy nosed and neon tetras, both of which I despised. Much more skittish and I'd find them occasionally on my floor, dry as a bone if I were to ever forget to replace the lid for an extended period of time.

It'd also help to know what other animals/plants you have in the tank. Some are just too fragile to go with anything that might be pushy/aggressive. Or some might appreciate a lot of plants more than others.

I haven't worked with any of the species you've suggested, as unfortunate as it is, although I'd place a nickel down for serpae tetras. They look kinda similar to bleeding heart except with longer, flowy fins. I assure you, though, they're two different species.