Well, these fish aren't really picky when it comes to food. they'll eat just about any type of food you throw at em. I think they're omnivores so blanched Romain or zucchini once every month could not hurt. live blackworms is also a good goto as well if u want to be zealous in your fish keeping. hmm personally for these guys I would probably keep a separate culture of gammarus shrimp for food since they are easy to culture
I used to own both and fed my tinfoils (literal vacuum cleaners) a mix of flake, bloodworms, peas (cooked+deshelled), lettuce, blanched zucchini and worms (chopped) when they got big. I focused a little more on plant matter and gave protein more as a "supplement"
For my sharks, they got something similar: bloodworms, tubifex (freeze-dried), worms (chopped) and occasionally shrimp (chopped, when I could get some from my friend) and flake/pellets
Both would occasionally get brine shrimp when I had to much from my cultures. They were great for thinning and cleaning them up