I have been retired for several yrs from the trade, but I was once a distributor (in Canada) for New Life Spectrum.
I still use their products. Not that there aren't other quality brands and formulas, but Tetra & Wardley have pretty much stayed the same with regards to their overall ingredients. The issue with terrestrial based plant matter is the inclusion of anti-nutritional matter. This can be largely reduced by processing temps, but still, IMO it is far more ideal to feed finfish, aquatic based plant matter. As an example, this is an NLS "veggie" based formula.
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I actually feed that formula a few times a week to all of my fish, no matter their diet category that an ichthyologist has placed them in. I think that it's fine to feed different foods, one just needs to be a little more careful with designer fish such as flowerhorn. Watch the crude protein levels, and crude fat, and while plant matter is good for a FH, I would limit the terrestrial based plant matter, such as soybeans, corn, and even peas - especially if in a raw state.
Feeding raw peas is old school, just like me, but over the years science has proven that terrestrial based plant matter is generally only used in fish feed formulas due to cost saving and convenience. There is no argument, probably hundreds of papers on this subject for anyone willing to do the research.
I'm not saying that a few peas here and there are going to be harmful to anyone's fish, only that today there are far better alternatives.
Peas contain phytic acid, tannins, and trypsin inhibitors, which are not something that fish benefit from and which can potentially cause negative health issues when fed in excess.
IMO aquatic based plant matter always trumps terrestrial based plant matter. I posted about this in the past discussion linked to below.
https://www.monsterfishkeepers.com/forums/threads/fruit-veg-for-fish.690291/