I've used the liquid fish emulsion in my gardens for many years, I love it.
The amount to use depends on three things: the amount of food in your soil, the nutrition requirements of your girls, and your feed/water schedule.
Start with 1 tablespoon per gallon, if the girls seem to be a little hungry, try 2 tablespoons per gallon, and so on. Once you see the first signs of nutrient burn, just dial it back a bit.
Fish emulsion is slow to cause nutrient burn. I think I've used up to 4 tablespoons of fish emulsion per gallon of water for my girls.
My watering schedule:
water, water, heavy feed, water, water, flush & heavy feed... repeat.
Since you'll be growing in soil, you should also supplement with a little molasses as well. In addition to adding more micro-nutrients, molasses also help feed the micro-organisms in your soil responsible for breaking down the fish emulsion into usable nutrients for the plants.
I use 3:1, emulsion:molasses. 1 tablespoon = 3 teaspoons, so for every tablespoon of fish emulsion, also add a teaspoon of molasses.
I've used up to a tablespoon of molasses to a gallon of water safely. Two tablespoons has worked for me in the past, but I've also had problems with that much sugar in my soil.
Also, I brew a compost tea with my fish emulsion, so my organic nutrient solution is ready to be absorbed by the plants once it's added to the soil. If you add your emulsion directly, expect to wait up to a week or two before your girls get access to all that nutrition (they will get a lot of it right away though).