I have purchased 3 zebra ottos from the ADC shop in London , they were kept in perfect form, well fed and on a tank by themselves. Got the home and started to feed them algae wafers, cucumber and potatoes. Did not seen them eating any of the above, but been noticing that the echinodorus leaves started to become transparent. At first I thought that I was missing any nutrient, but the ottos remained fat and always around the large echinodorus leaves. Then it dawned on me, one of the reasons I do not keep ancistrus is for that reason alone, they eat my echinodorus! So I you want to keep zebra ottos and are wondering what to feed them there it goes, large echinodorus will make them happy. . .