Flounders are very hardy...but your tank will be a little small for him after a few years. The zebra flounder grows to about 12", the peacock can go up to 16". They should be added to a well established tank, and NEED sand on the bottom, not coral substrate. The flounders I have eat freeze dried krill, and clam. They love to be fed directly, with a stick, you just wiggle the food in front of them and they'll snap it right up. Be careful with any smaller fish, if they get at them, they're dinner. They also come up on the glass sometimes which is really wild. I tease my son that they're displaying their filets for me to see if they're ready