I currently have a poly-culture of koi, goldfish, and bluegill. The bluegill are new this year and I have high hopes for them to replace the tilapia as a possible food fish. It was too cold here for the tilapia.

I love practicing Aquaponics.  The craft of it is a little tricky, but the rewards are amazing.  I would like to defend Aquaponics being accepted as ‘organic farming’ because it is a great way to diversify a growing operation, it is less labor, it is not harmful to the environment, it reuses resources a farmer needs, primarily water and nutrients, it can provide a farmer with a growing system that is not as vulnerable to pests and bad weather, we could do it in outerspace(cool!).  Yeah, I don’t like to use plastic, but we can learn to make plastic from plant based materials and/or natural materials to create systems that have very small carbon footprints compared to other systems (conventional agriculture), so I am for it.  I bought the materials for my system from FarmTek on a low interest loan and spent about three grand all together.  
Initially I had a hard time finding an OMRI approved iron supplement for the system, but I did find Bio-Min that uses citric acid to chelate the iron and make it available to the plants. I do not have a full load of fish so I supplement with Espoma Garden Tone that I put into the settling tank when my plants need a burst of nutrients during peak growing times. The acid nature of the fertilizer helps keep the ph down in the system and I use rainwater whenever possible. Initially I had not realized the relationship between dissolved minerals in our well water and the buffering of acid in the system water and the ph kept getting way to high, like 8, and my veggies would crash. Without the potassium carbonate and calcium carbonate from the well water, I can keep the ph around 6.5.

I am now working on grow tower designs made of polyethylene  bollards and see that as taking it to the next level of Aquaponics, vertical farming yo!  The bollards are around $35, you cut them and shape them with a torch and a dibble and oila, stick a net pot in the pocket and trickle water over them and you have aeroponics.

My rafts are made from polystyrene and covered with used round bale plastic.  If we must use plastic, at least we can take advantage of a waste product like bale wrappers that get wasted all of the time around where we live.

Deep water channels.
Media beds, celery in the top one and strawberries in the other. Strawberries love the a.p. System.