Right I couldnt see a brackish water section

so this wil have to do
I have decided to turn my 17 gallon into a
dwarf puffer tank and have been doing research into the sort of water and conditions they like (I did consider a
betta tank for a bit but 17g seems alot for 1 betta).
I would like some advice from people who have owned them, I am thinking of doing a 2g tank to breed snails in for them

. I have put my filter in the 125g tank to keep the bacteria alive, I am also going to cycle the tank again - is there much difference with brackish water?
I look forward to your advice and I will of course be showing pics when its all set up
