Where? I found the species
Danio kyathit as "fire ring danio" on Wet Spot's site, and this is the fish
@Essjay referenced on SF (
Brachydanio kyathit). The photo in your post #18 could be the same fish, but this photo seems to have been "touched up" so it may or may not be the same species. [The species was described in 1998 by Fang, but Kottelat (2013) considered it in the genus
Brachydanio which is SF's placement; Subsequently, Fang moved it back into Danio and Kullander and others accept this placement. Changing genera on SF is difficult so it will have to stay as is for now.]
If this is the fish under consideration, it will not work in a 20g high tank, as like its relatives it needs space to swim. The habitat description and the recommended tank size in SF explain this.
Brachydanio tinwini is another species in the same genus, doesn't seem to be what you are considering, but also active swimmer. BTW, photos of fish that are searched on Google cannot be taken as reliable unless you go to the site of the photo and determine the reliability. The photos on sites like SF, Planet Catfish, Loaches Online, CorydorasWorld, etc are reliable. I would assume those on Wet Spot are also likely to be accurate, but this can easily be checked by looking up the scientific name on SF or similar.