I also agree...they should be in a big tank. I have 3 that are about 8.5-9 inches and they still have growing to do. They are not to skittish, as long as you don't run up to the pond/tank (obviously). They are in my 450g. pond during the summer and are housed indoors during the winter so they need room to move. They will outgrow your 28g in no time at all.