help, adopted puffers, need brackish

I've got about 25 going in 30 freshwater tanks with all kinds of fish and some planted tanks. I liked some of the brackish fish but have never committed to getting a tank set up. Last night a friend called me in distress telling me he'd made a poor spontaneous decision. He was out of town (in dallas) and bought a couple spotted puffers, not sure on the species yet. He said they're 2" right now so that rules out the dwarf's for sure. The guy told him they were brackish but they would live in freshwater and he'd been keeping them in fresh. My friend took them home and dumped them in his 50 along with some bala sharks, silver dollars, angelfish, serpae tetras and emperor tetras and quickly found they were not quite adapted to the tank when they started shredding his mystery snails so after a little reading on the internet he figured out what was needed in a puffer tank and wanted me to find a home for them. Well...... My wife caught wind of this and went nuts for them so we're adopting them. I had a 20 high I just resealed and was setting up for some rams or apisto's but it was quickly hijacked for the puffers being the only tank we have available right now. I know the 20 is a little small right now but hopefully we can accomodate them to a larger tank later this year. Any tips on keeping these fish? we've had dwarf puffers in the past and know a little about them but the brackish is where my knowledge is lacking. I havn't seen them yet but I'm hoping to identify them in the next few days if I get a chance. It appears there are about 3 puffers sold as the green or spotted puffers (think they told him greenspotted puffer). Do they all prettymuch need the same SG? I'm running by the LFS today and will get some reef salt to use. I've got an idea of how to convert the SG to where I will end up but see if this sounds like a good idea. I plan to take a 5 gallon and set it up with water and add salt to the desired SG. On my weekly water changes, change 5 gallons with the brackish water. I figure if I keep doing this each week it should slowly raise the salt over a period of time, not sure how long it would take to get the tank fully adapted. Is this too fast or is it hard to tell? I've also been reading tons of conflicting info on plants for brackish tanks. Some lists have about every plant I have in freshwater listed to be adaptable to brackish, then I read a couple posts on here saying plants won't survive. I know many plants will survive because I've seen tons of brackish tanks in person at public aquariums and in pictures on the net and I havn't seen one yet that wasn't a forest. Mangroves are obvious but what else? Also, am I correct in thinking the 20 is a little small for the puffers or will they be fine? What kind of tankmates would they be ok with, in the 20 or a larger tank. I've always liked the knight gobies and archer fish but the archer fish would definitely be a much taller tank so I could do a biotope with insects but for future reference. I'll reply to this post when I get an idea what species I'm dealing with. KYle

thanks for the link RTR. I took a peek at them earlier and I think they are nigroviridus. the spots are not identical but I guess they are always a little different. One thing I'm not sure on is these both have a very dirty looking belly whereas the photos online show a brilliant white belly. is this common for puffers? they are about 2.5" long right now. the eye is blue in the center with a yellow ring around the outside. according to the puffer list and the link to wetwebmedia in the puffer list article, there are only 2 actual species sold that are like this and says it is highly unlikely they are the congo puffers. I finally got the story and found these were purchased at an LFS in Fort Worth, Texas as "green spotted puffers" and as the article states, misrepresented as freshwater. I guess as juveniles they are correct but the articles say they should be slowly converted to high brackish if not full saltwater. thanks for any info, KYle