What can help with algae in figure 8 tank

[enchanted]

http/www.floridadriftwood.com/algae_eater_flag_fish.htm

This one is supposed to be able to handle brackish, but that doesn't mean it's native to it or that it will survive your puffer.

Edit:
Mollies are great at algae removal. The problem is that they do best in brackish water

You could use Mollies, but same issue. They may not survive your puffer.

 

[subopposite]

I have a sailfin molly in my brackish tank and trust me, they are not good at removing algae. They may pick at it, but they don't suck the the glass and irradicate it. One could get a couple and there would just be a little less algae, but they aren't suckerfish, or at least mine isn't.