Flowerhorn like similar sized fish, astronotus ocellatus for example,
need a live food integration to be healthy and in shape. Their diet can
consist of live food, frozen food, and standard dry fish food. The live
food should be of good dimension, or the fish could not notice it, earth
worms and big meal worms or wax worm are accepted; moreover you can
give small fish, poecilia reticulata could be a good choice since the
high number of fry they spare monthly. Remember to feed every live
food you choose, and in case of live fish be sure they are healthy.
Frozen
food is another good solution, especially when you do not have the live
one. Young Flowerhorn usually eat chironomus, brine shrimps and other
frozen fish foods, while older ones could not notice them; at their
place you can offer frozen fish for human use, you have a great choice,
anyway if possible get freshwater fish and avoid the sea ones.
Both
live and frozen food can pollute the water, so be sure that Flowerhorn
eats all the given food in 5 minutes maximum, in case of rests remove
them fast; for this reason it is better to have an aquarium set up that
allow you to clean fast without needing to move objects.
Dry
standard fish food is a good complementary option, especially if it is
of good quality. You can find special foodproduced for cichlids that
usually consist of big pellets that Flowerhornlike.
A Flowerhorn
cichlid should be fed two times a day, everyday, anyway be careful with
the quantities and avoid to overfeed it, reducing the food amount
specially if it is really rich of nutrients.
source : http://frogstone-restday.blogspot.com/2009/11/feeding-flowerhorn.html