Feeders are thr very unresponsiable fish keepers food! They are trash. Dont use them its not worth it. And pellets dont have nutrition? Idt so. Massivor is amazing and the best supplement for big carnivors. Also danichi is really good providing way more vitimans then any frozen stuff will give. I do use shrimp as a treat tho
I only feed mine feeders on occasion to keep him happy. IMO, A fish like that would much rather hunt his food than just have it handed to him.
Most of what I feed mine is raw foods, mostly shrimp. All of which I let soak in a vitamin supplement while defrosting.
As for pellets; you're right about Massivor. Normally when I think of pellet food, I think of the cheap, empty, food designed only to fill the fish. I've never used any quality pellet foods before, so that was my mistake.
As for keeping toadfish in freshwater. They can be kept in full FW for some time, more or less depending on several factors. 6 months is not uncommon, neither is a year or two. Some people have had success with long-term FW toads also, but that is very rare.
The only way to ensure a happy, healthy toadfish is to keep it in brackish water, or even full marine like I do.
Is it possible? Yes, but very unlikely. It's very risky, and that's why most peoples' die; it's a risk I surely wouldn't want to take though