Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
The 'Dinosaur Bicher ' (Polypterus semegalensis) is a predator that can reach a foot long (and mine are still growing).
They dine on guppies (culls from my breeding efforts) as often as I put them in the tank, and I blame them for the disappearance of a few other fish, larger than Guppies.
NO WAY would they be OK in a 20 with small fish.
The largest snake/worm sort of fish that I would go with would be Kuhlie Loaches. There are dark ones (not quite black, but close) and a couple of species that are brown and gold.
Clear fish like Glass Cats or Pristella Tetras (a very easy fish) would look really good with moonlight.
If you are looking for fish with horror-names, how about Skunk Cories?