if your valentini is very small in comparison to your porcupine he may eat him or at least try if they are close in size you should not have a big problem all goes the same with agressive type fish if its small enough to fit into his mouth he could possibly eat him
In my experience it ust depends on the personality of the puffer. I have seen Porc never bother another fish and I have seen them eat anything they could get there mouth on... There is always that chance though
