What are the dimensions of that tank? It looks like a 15g to me, it's at least a 10. As for stockage, if it turns out to be a 15g, I'd put some your furcatas in there with either 4 scarlet badis or 4 sparkling gouramis.
Or you could fill it with sparklers and scarlet badis. Either way
Hmm?
It's almost 10 gallons. I had originally calculated ~ 7 gallons, but that was UK gallons, not US gallons. It looks bigger because it's 24" long. I built it myself specifically for a desk so while it's 24" long, its only 9" wide by 10" high. Also, for the record, the pics of the cardinals are from my 20XH at home where they currently reside