Depending where you look, bristlenoses come from fast flowing water (planetcatfish) but Seriously Fish comments that its precise origin is unknown with some people believing commercially bred bristlenoses are hybrids. But this is a fish which seems to do well in all types of tank with many different species. As long as there's a cave and some wood in the tank, water flow doesn't seem to make a difference.
The black gravel, if you rub some between your fingers does it feel rough or sharp?
Cories feed by taking a mouthful of substrate and sifting it for food then passing the substrate out through their gills. They can't do this if the particles are too large. Sharp particles erode their barbels; damaged barbels allows bacteria to get in and cause an infection. Uneaten food etc gets down into gravel and rots forming a breeding ground for bacteria.
However ..... bettas are not community fish. Despite what you may read on other sites, it is never a good idea to keep bettas with other fish. A betta may live peacefully for several months, then he snaps and goes on a killing spree. Or the other fish may pick on him. Even the most placid fish often can't help themselves when faces with long flowing fins. And there is chemical aggression as well as physical. Fish excrete pheromones and allomones to communicate with each other. We can't see these or measure them but fish will detect 'aggression' hormones in the water and it will cause them stress.
Bettas should be kept alone.
Thanks
good to know waterflow wouldn't be the issue re pleco. The black gravel doesn't feel "sharp" exactly, just sort of rough, like um gravel lol some of it is quite dusty tho, very fine, and I'm thinking it would probably be OK but now I'm a little concerned that corys prefer slightly cooler water than bettas anyways so.. just giving that some extra thought. I am now also wondering about tannins! But that's another thread
I appreciate the message again re betta being "fighters" though it really wasn't my question I know it comes from care and concern for these little beings we are responsible for as pet owners. And I'm aware everyone has different opinions and knowledge and experiences outside of this forum that they draw from, as it has been repeated I will just share my rationale for this idea just so you know that I am actually thinking on it, and I wouldn't take any action with any living being just on a whim. I guess I didnt think of having to explain myself in so much detail, I forgot what forums are like!
Its just that my understanding is that wild betta live in diverse, if tiny, communities in nature- males will often get super aggressive when defending their babies or territory against other males, that is true... and they were intentionally bred for fighting for a fair few decade's that is true; and there are plenty of stories where a betta mum or dad tried to introduce tank mates and it didn't work out, and it was very apparent very quickly, and there was a handy Plan B tank ready to go.
Very often though, when the space is large enough, when no body is stressed, and there are plenty of plants and hideyholes, a male betta will thrive in a tank with certain species of other fish without violence- smaller fish, who aren't too bright or long finned, and who prefer to occupy a lower or middle area of water, and who are faster swimmers (maybe that is a Just In Case proviso?)- including all the ones I mentioned earlier, and this set up actually mimics the bettas natural habitat.
While they can survive the sort of cramped solitary lives people tend to give them, they don't actually live like that in the wild.. true, they don't swim great distances, but they are never confined to "puddles" for long, as petshops and things will have you believe. Just google Thailand marshes, even the tiny underwater worlds of rice paddies- that's where betta will be, amongst many other bottom dwellers and midrange swimmers. So it just doesn't make sense to me to keep him on his own, unless of course he is a very aggressive individual, which will be apparent very quickly and for which there is a Plan B.
Almost all fish who are big enough have the potential to go on a nipping/killing spree, from the looks of things - I keep reading horror stories about people waking up to massacres with all different types of species... surely there would be many different factors including feeding/space/triggering changes in the environment etc that could cause something like that even from within the same school.
Anyway that's where my head is at though I appreciate everyone's opinion, based on the evidence to me at this stage, I feel like it's worth a (careful) shot.