hello torog, i have used store bought worm castings several times and have had great results, both indoors and out, however i have not tried to use guano or fresh fish. i have watered my plants with fish tank water that had lots of debre(fish poo, dead fish parts from a catfish fight, and old food particals) and the plants loved it. i plan on putting some fish in my plot soon so they will be a bit decomposed by the time i start growing next year because i've heard it works very well.