breeder steve runs aquaponics for marijuana, so did 10k from overgrow, and another guy from another forum I've seen.
breeder steve uses cichlids and has a interesting pH range of cichlids from 5.5-7.2 ish and keeps his pH around 6-6.5 he keeps oscars mostly and feeds guppies. he supplemented his water in a couple ways, he used dutch buckets which had a 1" layer of worm castings and such and he also added nutrients to the water which is fine so long as it doesn't kill your fish. another grow I saw used oscars and other amazonian cichlids and supplemented the water with dark or black river extract, look it up it's basically the tannis and stuff that tints your water greenish black it's not esthetically pleasing but it's far healthier for the fish.
pH is very stable, there is always going to be a wide range of nutrients available and it's important to have plants at different stages of life so that you use an assortment of nutrients available. needless to say :angele most available will be nitrogen.
Breeder steve claims to get yields rivaling traditional hydroponics and says it's because a ppm meter only measures dissolved salts but won't measure life which aquaponics is full of.
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personally if I ever go through with aquaponics I'd use cichlids, plecos, and scavengers - I'd be sure to populate the tank with plecos and scavengers before anything then add cichlids and such in.
Cichlids/other fish id consider are pike cichlid, canna "snake head", oscars, and amazonian cichlids. I'd keep enough drift wood and rock (both are essential to keeping a stable pH) rock generally raises the pH and drift wood lowers it.