Fresh veggies primarily consist of water, so nutrient wise ounce for ounce they really don't compare to aquatic plant matter that's in a dry form. I use NLS AlgaeMax as my go to veggie food because it contains such a wide variety of aquatic plant matter. Northfin has kelp as the main ingredient, but it's a long ways down the ingredient list before you see any additional aquatic plant matter in that formula. But of course what you feed is your prerogative.
Northfin Veggie:
Kelp, Whole Antarctic Krill Meal, High Omega-3 (DHA) Herring Meal, Whole Sardine Meal, Wheat Flour, Spirulina, Garlic, Astaxanthin (Haematococcus Algae), Calcium Montmorillonite Clay, vitamins etc.
NLS AlgaeMax:
Ingredients. Algae; Chlorella, Ulva Seaweed, Red Seaweed, Kelp, Spirulina, Wakame Seaweed, Whole Antarctic Krill, Whole Fish, Eucheuma cottonii, Spinosum Seaweed, Chondrus crispus, Whole Wheat Flour, Omega-3 Fish Oil, Alfalfa, Astaxanthin, Capsanthin, Zeaxanthin, vitamins etc.
Good luck.