How long have you had your fish? It took ours awhile to get comfortable in their tanks. The Gold gourami is very tame and will follow my hand around the tank as I try to get food down to everyone else. After a couple of weeks the Pearls in the big tank started taking flakes from us and it didn't take the opaline in there long to get friendly either. The Paradisefish nabs fingers (not bites, but is rough) so I quit feeding her by hand.
If your fish have been in your tank awhile and feel at home, start by holding a flake under the water, slowly swish it. If no fish comes to get it, let it go so it will drift down. Don't make sudden movements and be prepared to take your time and be patient. Try another flake the same way, even if they didn't eat the first one. If you don't get results, walk away quietly and come back in half an hour.
It helps if the fish are hungry and also if you have something they really like. I dip Tubifex in the water to wet it and wiggle it around. Even my Black neons will zip in and grab pieces of this. Not all my fish are crazy about the same foods, so try some different things. My gouramis are all pigs, so sooner or later, their bellies will get the best of them.
Be sure you don't have any contaminants on your fingers that could get into the water such as hand lotion, etc. Good luck!
