In your iAVs research (Mark) or aquaponics experience (Gary), have you come across viable fish species that don’t require ocean inputs?
We share your concerns about the use of wildcatch species in fish feed. Having said that, the aquaculture feed manufacturers have made significant progress in recent years in reducing the proportion of fish oil and meal in aquaculture diets.
Much of the seafood content of fish food now comes from krill. Another point to consider is that soybean and cottonseed meals are probably no more sustainable when all things are considered. In any situation where you relying on fish waste for plant nutrients, you are going to have to confront this issue. At this stage, I don’t know of any way that you can grow fish and plants at any sustainable rate without using a formulated fish ration. For what it’s worth, when you consider the excellent feed conversion ratio of most freshwater species….and the subsequent fertiliser substitution…..fish feed is pretty efficient stuff.
Mark adds: If one is prepared to learn about fish nutrition and implement one’s own fish feed preparation, it is theoretically possible to eliminate ocean sourced oils and proteins. However, this is a challenging prospect and will be strongly influenced by the species one is attempting to grow. The practicality of formulating one’s own feed is IMO not particularly efficient assuming one assigns any value at all to one’s time and efforts.
While on the topic of feed, I note that, from what I’ve seen of pricing on so-called ‘aquaponics’ related sites, their feeds cost from 2 to 4 times the price of purchasing from established feed producer outlets (not including shipping). I further note that both ’boutique’ (small scale niche hype) and the major commercial manufacturers do not formulate feed feeds to address/meet plant requirements from the ‘wastes’ generated.
Many feeds are also very high in Sulphur, Copper and Zinc (et al.) and relatively low in Calcium and possibly other elements depending on the brand and type. Most producers also add substantial vitamin ‘supplements’ and some also add antibiotics, none of which are required nor desirable in iAVs applications.
Furthermore, IMO, ANYTHING one purchases from the ‘aquaponics’ sources is vastly overpriced – everything! IMO, they are all cyber pirates predating on willfully gullible flocks of fools. I won’t name names here but will say that if the term ‘Aquaponics’ appears on the ad/site/page, then you can be assured that you are being ripped-off. Additionally, the equipment I’ve seen offered on such sites is inferior junk. There is no substitute for quality and no excuse for not shopping around for the best prices.