I posted in here earlier but I come back in and it is not here.....lol
You can feed your tang the Fresh Frozen Peas & Fresh Frozen Broccoli thawed, spinach, Nori, Seaweed selects, Macro Algae, Spectrum Pellets, Marine Cuisine along with a variety of chopped meaty foods. many of the foods you feed your fish can come from the grocery store.......
Lettuce does not have the nutritional value your tang needs...... Try to offer a variety of foods to your fish.....
Kaye