Hi! I want to know if there are any tall (~12 inches) and small (~4 inches) grass plants that can resist temperatures of up to 85-86 F?? Please let me know! Thanks!
You might try a search for planted discus tanks. There are a lot of nice ones out there with good plant selections and they are generally kept in the high 80's.
All Echinodorus species can, Sag's, Cyperus helfeni etc.
The issue is more low O2 at higher temps for fish, and then more CO2 demand, and higher metabolism of plants. So you end up with less O2 and higher CO2.
The plants are fine with the temps, as long as you add enough CO2, even 35-40C is okay for many species.
But as you go from 20C to 30C, you increase the MET rates 1.5-2x.
So you need more nutrients/CO2 etc.
If it's for apistos or Tetras or Discus, all fish which I have bred in planted tanks, stick with 82-84 F range, they do quite well. If ALL you care about is breeding, then use bare bottom tanks and plan on many water changes and focus on feeding live foods.
Otherwise accept some trade offs on the temps to provide a balance place for both plants AND fish, that is your goal, so bend a little for each.
They bred at 82-84F just fine.
Regards,
Tom Barr