Gts are omnivorous, wild specimens have been shown to have up to 30% vegetable matter in their diet. Feeding a diet too high in protein is not natural for them and the food can start to decay before it's completely digested. Some meat protein is fine and necessary but you must include vegetables in their diet. When the food rots before it's digested the gut is overwhelmed by a proliferation of bacteria what you see as white poop is the lining of the digestive system not IPs. Garlic helps to acidify the gut and reduce this bacterial bloom. Vegetable based foods are easier for GTs to digest and helps keep things moving along. Try adding some veggies (Omega One Super Veggie Pellets is a great food for them) and eliminating the Tilapia and carni sticks. Bio-gold is good for them too. See if this helps.