First of all how gallons is your tank? Also remebr plecos get big. Mine was as small as yours but now is 14 inches long. Most people with a tank 100 gallons or less only keep one pleco. Anyways when they are small feed each pleco a half a wafer then when there bigger give each one 1 wafer a day at night. When there much bigger give them one in the morning and one in the evening. That is how I feed mine. Also if your tank is under 100 gallons be prepared to rehome one of your plecos cause they can become very territorial.