…we have had a small disaster

Well Dear Reader…it has been a while since my last post, as well…things were going along swimmingly. The plants in the system were thriving, we had tried out different growing arrangements, tried new vegetables and herbs in the grow beds (and NFT) and continued to marvel at the rate of growth of all things lettuce! We had even increased the population in the Sump Tank (with the introduction of four more gold fish: the Tiger Team and Smudge) and had farewelled the last of the Barramundi, after discovering the last cold, still body—floating belly up on an unusually chilly-for-Brisbane morning. During the lead-up to the Last of the Barras episode, we had introduced some extra heating and some extra oxygenation via air stones; but methinks it was too little, too late. That was back in June, and we had moved on, by restocking Tank 3 with more ‘you-can’t-bend-em-you-can’t-break-em’ Jade Perch. Bless the Jades and their hardiness!

Days melted into weeks, with nerry a pH spike or an aphid outbreak. Cruisin’ as they would say.

But, alas, we are but human, and while we were on a rather happy and fruitful roll with everything, something just had to come unplugged, didn’t it?

I have to say that our aquaponics system is not particularly complicated, but I can think of two changes introduced to the process that contributed to the loss of approximately 50% of our semi-mature (6–7 month old Jades):

• with the advent of the cooler weather we had decided that we would not cycle the water through the whole system at night. The grow beds and NFT are out in the open, and with that surface area and the constant flood and drain action, we decided that the beds were acting like a heat-sink, and effectively cooling the fish tanks. A timer was fitted to the system to turn the water-circulating pump off at 6pm and back on again at around 7am.
• as water flow is our main source of aeration, and with this now switched off at night, we needed to ensure the fish had enough oxygen, so we installed air stones (stone-like bubblers that have air pumped through them). These were plugged in and run constantly, alongside the heating elements—except of course when we cleaned the tanks—they were turned off as a safety measure.

On Monday afternoon Chris gave the system a thorough cleaning. He has redeployed some older pairs of socks as filters on the ends of certain pipes in the system to catch the larger suspended matter, but essentially a cleaning requires all electronic gizmos to be turned off, while he syphoned and strained the water from the main fish tanks. He topped up the water, emptied the solids into the worm farm and turned the pumps back on (remember they turn off automatically at 6pm) and then he went about his other chores. What was not turned back on were the air-stones. 😦

So at approximately 6am on Tuesday morning he heard splashing coming from the tanks, and thinking it was the fish feeding (‘but hang on I haven’t fed them…’) he raced to the tanks to discover a swathe of the Jades in Tank 2 belly up and many more gasping.

It’s terrible. It is. He was mortified. I was sad but even sadder to see him so distressed.

So over the next few hours, and indeed day, we have pulled approximately 50–60 dead Jades, ranging in length from 10–15 cms from Tanks 1 and 2. I was fascinated by how many fish were actually in Tank 2, which seemed to fare the worst (approx 80% loss—I guess with the larger population, they used up the available oxygen faster). All the fingerlings in Tank 3 (they have been in situ for about a month) were not impacted at all.

So. What do you do? With this hard won knowledge you have to write about it and share with anyone who may also be running an aquaponics system…our mistakes can be others’ lessons.

But what of the fish? Initially we decided to freeze them all in small batches and slowly reintroduce them back into our backyard system as cooked ‘meal’ for our chickens—I dare say one of the best and purest form of protein they will ever get! But with an enthusiastic word of encouragement from my youngest son (“I’m sure you could eat them!”) I got terribly brave and gutted 15 of the largest ones, with the view to maybe deep frying them a la some rather rustic seafood meals I had in Spain in 2010. And with the ‘fish guts’ I made ‘Fish Gut Risotto’ for the chickens. I can see the screwed up expression on your face right now, but it seemed like the right and sustainable thing to do…not to waste a thing.

I cannot lie, during this whole process, my head got very busy with what I was doing—gutting our ‘baby’ fish, and I did have to lie down for a bit before I fainted.

Things are stable today. All the fish we said good-night to last night, are still alive and kicking and we are just glad that they did not all die. But it is a lesson learned and I am sure we will see some improvements from my very own ‘Improvinator’ in the system in the coming weeks as he works to make things better for all! 😀

A sad sink-full of Jades 😦