flowerhorns were produced by people, and didn't originate in the wild...
Just did some searching and the only problems they have caused so far are within the hobby - apparently within the hobby they have been breeding with some of the species that they originated from (including Cichlasoma trimaculatum and Amphilophus citrinellus ) and now some of these species are almost impossible to find in their pure state (ie without being hybrids of the hybrids!), although people blame this on shops/hobbyists not identifying and seperating their fish properly...
Either way I just don't see why we need to create new species of fish when there are PLENTY of amazing ones already! And if someone wants to own a ‘new’ species, just go and find one - there are plenty out there waiting to be discovered!!
All said, as I said before, this is just my opinion and I realise everyone has their own opinions and I respect that