Hello friends!
I am going to be adding a third tank to my collection this year. My son has been asking for a puffer fish, so I have started the research and have a few questions on tank set up.
1: what kind of substrate should i use? sand?

2: the only thing I can find at the LFS is Green spotted puffer or figure 8 puffer. both are brackish water fish. witch one should I go with? and is a single fish okay? (really wanted a dwarf or pea puffer) will mix bumble bee golby in as well with plenty of hiding spaces.

3: I am seeding a filter off my well established FW tank, will the brackish water kill the the good stuff on the filter?

4: live plants in brackish water, is it worth the hassle or will the salt kill them?

thanks Aaron