Re: Aquaponics: do you or do you not?
Tailor Made Fish Farm has an extensive (for us) hyonics structure, mostly producing various lettuce varieties, but also some herbs.We grow fish in recirculating 10,000 litre tanks in banks of 3 tanks, (i.e. one module). Ten percent (10%) or sometimes more of this water is replaced daily. This water replacement is one of the ways in which we underwrite the health of our fish.
The overflow water is stored, then used in the hyonics trays. The content of nutrients in this overflow water, in which the fish live happily, with minimal / insignificant disease incidence, is not sufficient to meet the nutrient requirements of the lettuce, and therefore mineral and trace element fertilization / augmentation is required for the plant crop to occur at all.
The water is NOT returned to the fish tanks after being used in the hyonics system.
We produce barramundi, which are an estuarine / salt water fish, to market mostly to the Asian restaurant live fish trade.
Our fish production this year should be in the 65 to 70 tonnes range. I do not know without enquiry, what our hyonic vegetable production is.
I do have a personal, adverse, view as to the suitability of the suggested aquaponics model.
1. The nutrient load in the returned water (from the plants to the fish) will always be too great for the fish to be comfortable in. Barramundi in a recirculating system live well in fresh water from our bores, or in salt at up to 32 parts per thousand from one of our bores. If water quality in the tanks goes off, the fish die. There is personal and associated experience using our systems to confirm this statement, including experience with the return to the tanks of hyonics water, with consequent gross mortality in market sized fish.
2. The hyonics water on any commercial scale will sooner or later contain synthetic pyrethroid insecticides. Insects love young lettuce, so if you want a crop, you have to do whatever it takes, which is legal. Returning such products to your tank will soon remind you why this is a bad idea.
3. Fish do not love excess nutrients, which is why we go to such lengths to remove faeces and suspended solids from the water, and diligently monitor our water quality parameters.
Germs and fungi love excess nutrients. What do you aspire to grow - fish, or germs and fungi? They certainly cannot co-exist!
4. We have a healthy scepticism (cynicism) about the received scientific wisdom , tried so much of it at such great cost.
What we do works for us. It may be that if you have a fish, perhaps Tilapia, which can live in mud, and is adapted to it , that it may survive for longer in conditions which barramundi would find toxic, but why would you, from choice, provide less than the best possible conditions for them to live in?
5. The nutrients we put into our system are fish food pellets which are just in quantities to be instantly taken up by the fish. We then use the system design to self clean and thus remove the faecal solids (and occasional vomitus). We dare not leave these excess nutrients in the system, and feed pathogens. It is incomprehensible to me why anyone would seek to run an aquaponics system in any other way.
Jeff Titmarsh, B.V.Sc.
Raymond Terrace Veterinary Clinic,
Shareholder and company veterinarian,
Tailor Made Fish Farm, Australia.