What do you get when you cross a sustainable fisheries bloke with a Permaculture Design Course? An Aquaponics system enthusiast, advocate and entrepreneur, that’s what.

Matt Spalding took our PDC last year and since then he’s been going gang-busters on learning + building home aquaponics systems, with a focus on fish health, as well as vegetable and fish harvests.

So – what was the inspiration to start building aquaponics systems? You seem to have thrown yourself into it…

Matt – I spent many years working on commercial fishing vessels around Australia, a few years working in fisheries management as an ‘at sea observer’ and studied marine conservation and sustainability at the maritime college in Tasmania.

I’ve always had an interest in fish and the sea, however, from where I sit and from my experience, I believe there is more that can be done to ensure healthy, thriving and productive wild fisheries.

Aquaponics shone through to me because of this issue. Obviously there will never be a better place for fish to thrive, reproduce and be caught to supply the world with food than the ocean.

But until we can master how we do that, selectively, sustainably and ethically…

Aquaponics provides a great way for us to supply OURSELVES with fresh, local, sustainable, cared-for fish…. And vegies!

When I drove to Kangaroo Valley in late 2014 to take part one of Milkwood’s Permaculture Design Courses, it would be fair to say I didn’t know too much about aquaponics.

[but during his PDC, Matt got extremely excited during Floyd Constable’s Aquaponics how-to sessions, and then there was no stopping him]

I have since built a number of systems that continue to produce loads of food, fish and entertainment, I have started my own business in aquaponics and am looking to travel abroad later this year to connect with like minded aquaponic-y folks of different cultures.

[As the only student on his PDC that couldn’t help but take off for a quick fish in the Kangaroo River during lunch break, this all makes so much sense now]

What type of fish are you using?

I am using goldfish, rainbow trout and silver perch.

Goldfish are a great fish to use, entertaining and resilient, they will follow you as you walk around the tank and nibble at your fingers and arm when you stick your hand for what ever reason, it would be a hard day for me if they were grown to harvest.

Trout are more full on, they are a little less resilient to changing conditions. They love faster flowing, fresh, cold water.

If you can provide this, then trout are the go – fast growing and fast metabolism, which means lost of nutrients for your plants.

Silver perch – I never tend to see our perch too often, we have a 5,000ltr tank dug into the ground, inside a hot house. The tank has some structure for the perch to live around and over half of the tank is shaded.

If you go to the back of the tank, and peer under the cover, you can see them in there, happily swimming around in a slow current that we have provided.

Perch are a much slower growing fish to trout, but are proving to be a strong and easy to grow fish to keep long term down in Victoria over the changing seasons.

My main goal is to have happy fish. While these are farmed fish, they still have all the makings of wild ones, you can see it in how a Trout feeds or sits in a current.

So overstocking is something that I am very conscious about, some people like to get as many fish into one space as possible. I am of the opinion that while they are in our care, it is our responsibility to give them the best quality of life we can.

However, I have also noticed some fish stress in understocked tanks – so there is a happy medium, enough to school and feel safe, but not crowded.

Next on my agenda of things to learn about growing my own food for all my fish, as some of the high protein fish food that I use contains wild caught fish.

I grow worms for our fish but would like to look into growing crickets, cockroaches and other creepy little things that could be used for fish food (and/or practical jokes).

Can you tell us a bit about your two-bathtub home aquaponics system? 

The two bathtub system is the first system that I built, it was thrown together pretty blindly but with a lot of enthusiasm and has had its fair share of issues.

I built this system at my parents house after finding a space that has never really been used for anything.

I found the bathtubs at a local second hand building supply joint. The IBC from the classifieds and the rest from the usual places.

I decided to go with goldfish due to their astounding ability to forgive me as I stressed them out with my continual changing of things as I learnt.

The whole system including the pergola type thing cost me approximately $600, give or take.

I put the roof on because of a very old and very large pepper corn tree above, dropping leaves with every southerly gust – which I didn’t really want all through my system.

Can you tell us a bit about the climate you’re growing in, and how you’re overcoming whatever challenges are particular to the site to get good growth?

I am growing in a temperate climate with bugger all rainfall. Which is another reason why aquaponics is an appropriate way of growing our own food, as it uses a fraction of the water that dirt gardens can.

My father and I built a rather large hot house for Mum for Christmas.

We looked into buying ready-made houses but they just proved to be way to expensive for there size. Dad has a long history in building and has adopted the name McGyver for he’s improvisational building “skills”.

So we got brainstorming and started building the hothouse out of some old temporary fencing that we found and a bunch of other miss matched bits and pieces.

This is not the ideal way to build something and looking back, we did quite a lot of things backwards.

Buts its all part of it isn’t it ?

The hothouse system is powered with our Silver perch, which grow faster in warmer water but can withstand the cooler months too.

The outdoor systems are now powered by trout, which were put in at the beginning of Autumn, (maybe a little early) – these guys will mature to plate size before next summer and I will then stock with Silver Perch.

A common practice with alternating these two species is 6 months trout, 18 months perch, 6 months trout, 18 months perch.

This gives the perch a summer to pack on some meat to get them through the winter, pack it on again over the following summer and be ready to harvest before winter to make room for Trout again.

So its just about taking notice of your climate. We could theoretically grow any species down here, with the help of water heaters/coolers etc. but whats the point?

We want to put as little energy into these things as possible – so it’s all about working with your climate.

I can see you have big plans for your aquaponics ideas – what’s the next build?

Who knows?… Barramundi on Mars? Moon Trout? Baby steps…..

I have been thinking a lot about swimming pool conversions lately – I have a picture in my head of a green sludge filled old pool that no one uses anymore, transformed into a beautiful, pristine, flowing fish habitat.

Perfect for swimming in, snorkelling, spear fishing, bringing in all kinds of wildlife, while feeding massive grow beds of veggies.

I would love to set up a community project, a non-profit type project where everything grown gets donated to a local cause – we could involve schools, or people in need. The possibilities are endless, really…

Thanks Matt! We’ll be checking out Matt’s further aquaponics builds in the months to come. Matt’s Aquaponics is based in Geelong, VIC.

And all our articles, how-tos and resources on DIY Aquaponics are here…