pimafix and melafix are both very potent anti bacterial/fungal treatments and generally not safe for airbreathers as they leave a film at the top that ingested in large amounts is lethal... that being said i do use it on airbreathers with extreame caution and in much lower doses then reccomended.
no not the same as bleach, but potentially just as dangerous. on a side note.. pure ammonia is great for cycleing a tank... and much cheaper then useing " instant" cycle products which imo are useless. But i prefer useing a few pellets or other food to cycle a new tank. or adding a cycled filter to a new tank/ setup and cycleing the new filter off the old... ect... Cycles are called this for a reason... no such thing as an instant cycle.. you still get mini cylces if not tended properly can put to back to square one.