Having a pellet that isn't pellet shaped is another (I think). i.e. RES have been notoriously hard to pellet train. Optimal Bluegill food isn't shaped like a traditional oval/round pellet. Is that the reason why RES are much easier to get pellet trained, or is it the food formulation? I'm leaning towards the shape, then once they taste it, they continue to eat it.
Here is my 2 cents after feed training a small number of RES every year over the last several years. There are are likely several things going on, the most important in my opinion is that non-hydrated pellets are simply not easy to crush with the pharygneal teeth in the back of the throat in smaller RES. Taste, texture, and shape may also play a role as well. The small number of RES I have in my aquarium right now still frequently spit out the Optimal when it is first fed and really don't get going on eating it until it has hydrated and softened a bit. I will say that they do seem to like the taste of Optimal way better than Aquamax, but both types of feed are regularly spit out until it has softened. The optimal they will eat after it has softened, the Aquamax not so much. I am thinking RES would take to eating pellets much better if the feed was formulated more like soft dog food is.
