The stores around here will usually give 1/3 retail value cash or 1/2 retail value store credit, but only for fish that they need or think they can sell. I have rarely taken fry into a store and been told that they are 'large enough'. I took in 1" bn plecos and was told they wanted them 1.5" (but they took the 1" fish anyway), and when I came back a few months later with 2" fish they said they wanted them larger still...