My experience - I started my first saltwater tank a little over two months ago, and introduced two clown fish + 1 Sailfin Molly about 6 weeks back. And I have been feeding them flake food all along. Yes, the clowns were near the bottom in the first week. Guess they felt safer there. Then they took shelter behind the powerhead and sometimes next to the heater. Basically wherever there was minimum flow. And then they started going all over the tank (40 G breeder tank). I lost one clownfish along the way. My LFS concluded I had slightly high ammonia which one clownfish was able to withstand, but the other couldnt. I also noticed that if I powder the flake then it is much easier for the clownfish to take. They were very young and had a very small mouth. They couldnt bite off a larger sized flake. Other than this, I dont see any issue. They sense it as soon as I introduce the food in the tank.