need some info

[bicky1]

I have a 75 gallon tank with 2 columbian blackfin sharks, 1 archer, 1 spotted puffer and a pleco. Is this a good setup to start a brackish tank? Any help would be appreciated.

 

[f8fan]

Plecos are freshwater fish, and the other inhabitants that you have are high-end brackish. What is your salinity at right now?

Also, those catfish are gonna be tank-busters...They can grow to a foot long.

 

[Dragonet]

Kellys right those catfish will eventually become to big for your tank and will have to be moved.
Also plecos are very sensitive to saltwater and cant endure what your brackish-water fish are going to need.

In terms of high-end brackish fish you might want to start with something a little easier and hardier like scats. They are very hardy, have ferocious appetites and are easy to progress to full saltwater.
I used to have one before i found out it was a brackish-water fish. But when I did have him I had him in full fresh water for almost a year and he was perfectly fine because they are such a hardy fish.
I later gave him away to a brackish-water keeper.

Liam