Excluding macrostoma (they are a touch more sensitive), I found my mouthbrooders have been the most tolerant of any of the wild bettas I have kept. My albis and channoides didn't care what conditions I housed them in and my unimaculata male is living happily in a community tank down in my rumpus.
I don't bother worming my wild bettas. Metro needs a vet prescription here so we have to use a pig and poultry wormer instead. Only once have I had a fish (not a wild species) sick from a large worm load he was carrying. Except for the velvet my wild bettas have always been in top notch health and breeding form.
Other medications are also severely limited here. I was using a brand of medication called Ichonex that had copper sulfate or something similar along with malachite green. I know copper can be dangerous at lower pH levels but all my other fish and fry were treated with it to no ill-effect. Tanks were also blacked out, and temperature raised to around 30 degrees celsius.
My other fish have shown no signs of the disease returning. It is very difficult on these species to firstly get a good enough look at them and secondly to differentiate between velvet and natural iridescence.
I do have some malachite green and formalin, but it has absolutely no dosage instructions whatsoever. This is what I pulled off their website:
Short bath 2-4 minutes per 10 litres for 1 hour, once a day for 3 consecutive days.
For long term use use at a reduced rate of 1ml per 40 litres.
But I have no idea how toxic those ingredients are and how long I can dose it without it making my fish keel over.
Anyway, here are two very poor shots I got of my kids yesterday while fiddling around with their tank.
Don't know why the red shows up so strongly in photos. One of them in real life has a completely blue tail now and yet it still looks red in the photo.