No it does not need more fish i have been running more with the same out side I just moved inside because of my dog would not leave my pumps alone. As mentioned I grew bell peppers and squash from these same fish. I could add more fish but it is not necessary I assure you.
With talapia you can have 1 fish per gallon they can live (while I doubt happy) with that ratio. Gold fish need a lot more space or they will get stressed and or sick.
Look at the plants they are very happy the veggies are 3 weeks old with some new lettuce and parsley at 1 week old.
Added the t-5 lamp and moved the mj sprout to a different position under the lights.