Newbie to puffers, couple questions

[Torric]

Hey all, new to the forum and puffers in general.

Little back story, I had done a ton of research before ordering myself 2 figure 8 puffers. Had a 20g tank set up and converting to brackish, started a snail culture (unsuccessfully... maybe?). After several orders come through with no puffers due to one reason or another, puffers finally showed up! After the initial excitement of puffers ACTUALLY being in the box subsided I noticed a problem... the 2 figure 8s I had ordered and started preparing for we’re in fact 2 green spotted puffers. Whoops. I know that my 20g was a bit of a squeeze for 2 figure 8s, but now I got these 2 chunks. (My wife instantly fell in love with them but hates the space I take up with my little hobby but I’m working on conning her into a new bigger tank).
So that leaves me to my question, any tips for a new GSP owner? Been feeding them blood worms and brine shrimp with a few snails here n there. And just picked up some clams the other day. Will they self regulate their teeth? They just don’t seem to be biting the shells of anything.

I’ve seen conflicting things about the black belly thing. Is it normal for it to come n go over a few seconds? Seems just to be one of the two doing it.

Thanks!
PS. Sorry for poor formatting, thinking And typing on the fly here.

[Pufferpunk]

Great info in our Library on care of your puffer and feeding, Etc. How did you cycle the tank?

[SAPpyPuffer]

GSPs need a lot of room, and can get quite nasty, even with each other. Fully grown, they will need more than 20g, and though brackish is fine right now, they will thrive the most in full marine as adults. If you keep them, good luck, but be prepared. I find that GSPs are the most mistakenly bought fish, as so many people don’t know what goes into their care (even Walmart used to sell them!). For feeding, snails work, but try to vary their diet with bloodworms and crustaceans. The puffers might get the hang of clams, but easier food is better. GSPs can be little piggies, so feeding shouldn’t be a problem. I’d say the thing that most people are unaware of is that they are marine puffers.

[Torric]

I have done a fair amount of research. I know they need a much bigger tank and have been keeping an eye on their interactions both with each other and the tank mates. And just to be clear, I did not order the GSPs. There was a mistake made on the sellers part and that packaged the wrong fish. When I talked to them about it they basically said “congratulations on your new fish, good luck” (post refund however).

When I originally set up the tank I used a filter from an established tank, ran it for a few weeks. It was initially set up for freshwater but looked into how to transition it to brackish and have been raising the salinity by .002 ever week or two so as to not lose my cycle. Currently at around .008.

I’m feeding them a variety of frozen food in addition to snails and clams. Brine shrimp, blood worms and krill (they seem to hate the krill, nothing eats it).

[Pufferpunk]

Running an established filter on an empty tank pretty much kills off all the good bacteria. In essence, you have a non-cycled tank. Have you been watching their parameters closely? Will you be able to upgrade them?