-germ-
Rheophilic....
As mentioned a sec ago by boyneburn they'll will spawn much more readily if alone, do you have a spare/hospital tank?
If so use it.
In a community if they do spawn i doubt many of the fry or even eggs would survive but theres always a chance and those that are eaten will provide good nutrition for your other fish.
If you want to give them their best chance in a community add the marbles/large pebble substrate, if you are convinced you want them all to survive then set up a new tank and (as boyneburn said) remove the parents as soon as you can after spawning....
If so use it.
In a community if they do spawn i doubt many of the fry or even eggs would survive but theres always a chance and those that are eaten will provide good nutrition for your other fish.
If you want to give them their best chance in a community add the marbles/large pebble substrate, if you are convinced you want them all to survive then set up a new tank and (as boyneburn said) remove the parents as soon as you can after spawning....