I use soil blocks all the time, mainly with worm castings. Never thought of making fish feed blocks. Going to have to give that a try.

I've been looking into attracting insects for feeding the fish. Keeps them away from my plants. If you are using a blender then insects could be added to the mix. Its easier to set up a light trap that collects the insects in water. A swirl filter also seems like a good place to have a light source over. Does not effect the fish and is easier to keep an eye on.