Sand?

[Byron]

I forgot to mention previously (post #43) that the barbels are clearly another example of evolution to benefit the fish. The species of fish that have barbels would have been seriously compromised without them, which is why the organs developed. Some fish that have them have poor eyesight, some are nocturnal, etc. I don't think Corydoradinae have especially poor eyesight, but eyesight is of no benefit whatsoever in finding food that is down in the substrate.

 

[Stan510]

We probably have no idea of what the many different species of fish and what their barbels are capable of. We can guess they are for vibrations..but who knows how much more they can do like scent or pick up electric signals of prey in the substrate...hormones to find mates.
They are not there for decorations.

 

[sparkypenguin]

Thanks to everyone for all their input on this topic and whilst I'm still only a newbie what I've learned so far is that it makes total sense to try and replicate any fishes natural habitat as closely as possible.
This includes but is not limited to water flow, PH, Hardness, temperature, the number of that fish, tank mates, light and shading, hiding places, bog wood, rocks, plants and obviously the actually substrate.
For any bottom dwelling fish or fish that engage with the substrate it seems total sense that it is vitally important.
Hence if Corys. Pandas in my case, are naturally found in fine smooth substrates then we should keep them in fine smooth substrates.
I very much doubt that their flat bottoms evolved from living in rough gravel and my current thinking is that any effects of tank breading is highly unlikely to override millions of years of evolution.
However this does not mean that they will not survive, breed etc in a gravel tank, especially smooth gravel, but it is likely that their quality of life and therefore their lifespan will be lessened.
Hence I will be changing at least a large portion of my substrate to sand.
Thanks again to everyone.