Tropicaltoba, i dont really feed my fish, i keep goldfish and some native species, which i want to replace with goldfish ultimately. I have bought 1 goldfish feed this summer, very small quantity and that was all i fed them the whole summer. I dont usually feed them becouse i have introduced river crustaceans, dunno which species but are very small and have a stable poppulation of theese. I also have dragonfly larvae ,some stranje muck worms that show themselves trough the muck , and all other kinds of nasties.
My ponds are not heavily stocked with fish, so what in there naturally is sufficient at this point.
For the mosquitos i dont really know if the ponds are making a dent in the poppulation, i have never seen a flock of musquitos like flying above them. Ive seen them laying eggs on the water's surface, and i do have a substantial amount of mosquitos in the yard in spring and early summer, BUT at that time wherever i go there are awlays alot of mosquitos, forests are the worst place to go with summer outfit lol.
Ive red there are some biological means of controlling mosquitos in ponds that do work, i just let mine run as naturally as possible, i will possibly get more goldfish this summer, this should help with their control.
Also if you make a pond u can add a strong watterfal or some kind of watter aggitation device, mosquito hate moving highly oxigenated water.
Sintetic ferts, i use whatever i get my hands on..npk ones, micronutrient ones, i found a hidroponic store where they offer some stuff that is usually hard to find here, like terra aquatica brand along others. I also use kristalon, which i think does a good job.
Here are both of them right now.

