Neptune's Harvest is the fish fert that I use, and you can find it online.
http://www.neptunesharvest.com/
this is the stuff i use.........i use a plastic syringe thing and add it directly to the pitchers.......i have really gotten away from chemical ferts, mainly because my ground water is already full of salts and i dont want to add more inorganic compounds to my soil.....since i have organic ferts for my out door gardens they are what i use inside aswell