yep all my fish eat exactly that, they have since the start and are doing very well
But I use a variety of foods, at least once a week is frozen brine, at least once a week is a cucumber slice (comes in a little seperate pot of salad from my take-away man, and well if he thinks its for human consumption i assume its clean enough) and about twice a week is that packet food and an algae wafer for the shark (though in summer my algae has increased so i havent bothered with the wafer)
That same manafacterer (?sp) makes a really really poor algae wafer that turns very quickly (as in on contact with the water) to sludge that can do little but pollute your tank and feed very little
I find that those small pieces are great for feeding a timid fish, they float really well but if you drop a drop of water you can get a fairly controlled small amount of food to fall down so a fish not willing to come to the surface can eat it as it slowly falls, I feed one of my Rosy barbs like this twice a week as she doesnt often approach the surface even though she is one of the biggest species in there (the shark obviously isnt up there competeing and he is the only larger fish than a rosy tetra)