2x 3inch GSp's Need Help

[colebar1]

So I had a ad up online looking for a 3+inch Green Spotted Puffer for my 55g Tank. I have it 1.008 salinity for my old figure 8 that i had before giving buddy to my brother.
Well to make things short a gentlemen emailed me stating his tank has a crack and is leaking very slowly. He told me that these 2 gsp's he had are about 2.5 inches in length.
And if i didn't come get them that night he would have to do something with them. So i went to his house and had them bagged up already to go. they have to be almost 3.5 inches in length.

I told him they would be going in a high brackish or marine tank and that's when he told me that he bought them as babies about a inch in size 3 years ago and they have been in freshwater with just normal
Aquarium salt. Couldn't believe what he was telling me. One has some Green On the top of him and the other is just all yellow no green at all.

So they seem to stick together in my 55g. Water parameters 0 Ammonia,0 Nitrite, 0 Nitrates and i have dropped the salinity to 1.002 cause he had them in freshwater.
Now at there age and size should i be able to bump the salinity up daily? Dont care about my filter bacteria as i can get full canister of media from my 100g Reef tank.
Would like to go high brackish 1.021 or full marine depending on whats best for these guys?

kinda in a panic with them as one minute they are fine swimming around exploring. the next they are in mangrove root ornament with a little bit of a grey belly starting. then back to swimming fine and dandy almost pitch white bellys then back to in the mangrove with grey bellys.

[Pufferpunk]

I really hope you are keeping a VERY close eye on those parameters, testing daily. SW bacteria & FW bacteria are different. At BW, you have some of both.

My best suggestion for you is to remove them into a bucket & set that tank up as marine. Sounds like you can take all you need from the reef tank. You can drip-acclimate the fish using water from your reef into their bucket as you are changing out their tank.

[colebar1]

Been testing twice a day. doing 40-60% water changes depending on parameters. Tank was cycled at 1.008 but its down to 1.002 right now since these guys came from a freshwater tank and its causing my nitrites to rise. Going to start drip acclimate them now and bring my tank up to full marine salinity. not looking forward to the cost of salt this month haha
They tank is in my living room so i can see them all the time. I was going to put them in different tanks but they seem like they are attached to each other. they follow one another around the tank all
the time. haven't seen any aggression either so i think i will keep them together like the previous owner. Still in shock he had them in straight freshwater at 3.5 inches in size. Ill try and get some pictures of them tonight.
Also have my Canister filter cranked right up to the max flow so about 350gph.

[colebar1]

Checking parameters twice a day. I would put them in my reef tank but i have some fish i want to not become dinner haha.
Going to put them in a bucket and drip acclimate them as i setup my tank for marine with 50% water from my reef tank

[bertie 83]

Yea you are best off starting at marine. Remember to add some established filter media and or live rock from your other system

[Pufferpunk]

There's usually no filter media used in a marine system.

[Welch4]

There's usually no filter media used in a marine system.

I've always viewed live rock=filter media for marine.