Anyone who fishes irl knows what chum is... it's usually a bucket of stinky left overs from cleaning fish mixed with miscellaneous other items and dumped in the water to attract more fish. It's a pretty disgusting soup of garbage that fish seem to find delightful. So my thought is we could possibly have school specific "Chum" spells that would increase the likelihood of finding fish of that school. When cast it would act in a manner similar to Summon Fish but as it re-populates the fish in an area it would increase the chance for a percentage of the new fish to correspond with the desired school. For people in search of a specific fish... Frost Dekoi for instance if you're crafting an aquarium... cast an Ice Chum spell and have a better chance of finding ice fish.