I love the convenience of these parchment bags. Of course you can make a parchment packet with a roll of parchment paper. I made a video on my Shiitake-Ginger Bathed Fish In Parchment when I was unable to get the bags and used a roll of parchment paper. It only adds a minute!
I have made this dish with both salmon and sea bass. Both were excellent. In both cases, the portions were thick (about 1 inch). Barramundi and other firm fish would work well also. If you use thinner pieces of fish reduce cooking time slightly. Accordingly, increase if you use thicker pieces. It's a forgiving cooking method though, and you're not likely to end up with dry fish!
Season with salt lightly. The pesto may already be pretty salty. I use a salt grinder, and just do a couple of grinds when I toss the veggies.
Macronutrients (approximation from MyFitnessPal.com): 37 g protein; 26 g carbohydrates; 31 g fat. Note: I used 5 ounces of salmon per serving (splitting the suggested 4 to 6 ounces in the ingredients). You can certainly reduce the salmon portion to trim some fat and calories while still having adequate protein.
I typically use smaller (salad sized) plates as they give a bigger impression! We watch portion sizes closely.