Have you tried this with dario dario? Or with others that are considered "live food only"? I'm thinking gel in the fridge would go over much better in my house than worms in the fridge. . .
I don't have Dario Dario, but I was amazed that my sunfish pick at it and eat it. Up until this food they would ONLY eat live worms and occasionally they would snobbishly agree to some frozen bloodworms, but they will eat the meat pie and pick at the shrimp souffle. I was quite impressed. My breeding Peacock gudgeons will eat flake if they have to but they prefer live food and they also eat this stuff up. I don't know that it will work on every predatory fish, but I thought I would add in that experience. =)