Hi Manoj,
I don't think you should experiment with any "extreme condition".
Having said that, if you're not sure if you can house Datnoids, it will be cheaper to get American Tiger (Silver Dats, Datnoides Polota) rather than Indos.
Approx cost of ATs (~2.5") is about 100 INR. Costs of similar sized Indos is about 2000 INR.
Also note, Dats are very very very slow growers. So be prepared to keep a 50-90 Gal tank reserved for these dats till they can be housed with your Silver Aro and bichir. (Your RTC might be already be too big for any indoor tank by then.)
Good luck,
Sid