Dog food is designed for dogs. NOT for fish.
The problem with most dog food, including this brand, is that it is typically too high in fat for tropical fish kept in captivity. This brand, like most, is also high in the wrong type of fat (Omega 6) and low in the correct type of fat (Omega 3) especially for a SW fish such as a V. lionfish. Many fish won't do well on fat such as Canola Oil, especially marine species. SW fish will do very poorly on any type of fat derived from terrestrial based plants.
Also, while this food may be "grain free", the 3rd, 4th, and 8th ingredients (quite possibly the 1st or second ingredient when combined?) is POTATOES. I do not know of a single species of fish on the planet that consumes POTATOES in its natural environment, and again, it's a terrestrial based food, that is very high in STARCH.
This is why fish eat fish food, dogs eat dog foods, and cats eat cat food. If you don't understand the science behind commercial foods you're far better off letting the animal nutritionists do the math for you.
Ingredients
Salmon, ocean fish meal, sweet potatoes, potatoes, canola oil, salmon meal, smoked salmon, potato fiber, natural flavor, salt, choline chloride, dried chicory root, tomatoes, blueberries, raspberries, yucca schidigera extract, dried Enterococcus faecium fermentation product, dried Lactobacillus acidophilus fermentation product, dried Lactobacillus casei fermentation product, dried Lactobacillus plantarum fermentation product, dried Trichoderma longibrachiatum fermentation extract, vitamin E supplement, iron proteinate, zinc proteinate, copper proteinate, ferrous sulfate, zinc sulfate, copper sulfate, potassium iodide, thiamine mononitrate (vitamin B1), manganese proteinate, manganous oxide, ascorbic acid, vitamin A supplement, biotin, niacin, calcium pantothenate, manganese sulfate, sodium selenite, pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, riboflavin (vitamin B2), vitamin D supplement, folic acid.
Crude Protein 25.0% Minimum
Crude Fat 15.0% Minimum
Crude Fiber 3.0% Maximum
Moisture 10.0% Maximum
Zinc 150 mg/kg Minimum
Selenium 0.4 mg/kg Minimum
Vitamin E 150 IU/kg Minimum
Omega-6 Fatty Acids * 2.4% Minimum
Omega-3 Fatty Acids * 0.3% Minimum