I think it's pretty safe to say that FHs are omnivores because most are a mix of a few different species from multiple genuses with different dietary requirements.Consider that in nature A trimaculatus is an advanced predator (by analysis of wild caught individuals stomach contents),
but then what it is hybridized with to get a FH.
Some say Vieja, a frugivore (a fruit eater) or......
if it a one of the Herichthys, primarily omnivores, that when stomach contents of wild caught individuals are analyzed is often 50% algae.