Any change in diet takes some "work" to get fish accustomed. As spidangular suggested, holding back food altogether for a day or two will do wonders in increasing appetite. Some fish will just be stubborn as heck and may still refuse anything but what they've become accustomed to. So it takes a bit of observation to just make sure they take to the new food.
When you get new fish, it can sometimes be a guessing game to figure out what they've been fed (there's usually a "one food") for most of their lives; pellets, cheap flakes, live, frozen, etc., etc. I usually start with a good high-protein flake that proves acceptable. Then I start mixing in other types of flakes in the same feeding. I just take a small pudding cup and mix varieties of flakes. If they don't take frozen foods right away, I'll try freeze-dried. If they accept FD, then I start wetting them before offering. The last step is to thaw some frozen with FD and feed the mixture. The FD is eventually phased out as a staple.
Just a word of caution on some of the prepared foods you've tried. Egg parts, yolk or whites can foul water pretty quick. So if they don't take to it quick, remove it quick. It may be a bit of work, but if you can separate an egg, try poaching an egg white with some flakes mixed in.
Heck, if we can cook for pets with fur, why can't we cook for pets with scales, lol!
