Hello, I see you tracked me down!
Tank is looking nice, even if I do say so myself. Looks like the Reni is colouring up nicer then it did for me. I've always been scared of a Soroity just purely incase it goes wrong, however as I said I currently have a 8 Gallon that I can split and 2.6 Gallon Empty so can house up to 3 if needed. I'll leave them empty until you're happy you got no major issues.
Personally I have heard that 15g can work although I would be more comfortable with a longer, shorter tank. A basic 20 Gallon long would be better I feel. That way you can place in dividers and house 4 in one tank if things go wrong!!
I also think that there is too much open space in the middle, have a look at some suction cupped plant pots maybe to break things up, I'd also want to get some wood into the tank somehow but that's just me and I have so much moss around I don't know what to do with it.
All in all I know you know what you're doing but I still wouldn't be comfortable, however saying that possibility of free fish..... go for it?
Kojin's Keeper Since 08/11/2018
Ouro's Keeper Since 13/12/2018
Opal's Keeper Since 21/01/2019
Rose's Keeper Since 11/03/2019