Trout in Aquaponics

There are three main species of trout that can be used in Australian Aquaponics systems including: brook trout, brown trout, and rainbow trout.

Rainbow trout are a cool water species of salmonid which are distributed widely around the world. They have been cultured and stocked into dams and rivers in every continent except Antarctica, and are possibly the best known fresh water sporting fish in the world. Rainbow trout prefer cooler water temperatures, with optimum growing temperatures around 13˚C (56F) – 17˚C (62F). They can tolerate temperatures as low as 3˚C (38F) and as high 24˚C (75F) but not for extended periods of time.

In locations where there are wide temperature fluctuations between summer and winter, like Australia, trout can be an ideal winter crop with a really fast growing time. In areas with cooler seasons trout make an ideal all year round fish species for aquaponics.

If your going to keep trout at home in the backyard- having a larger water volume in your fish tanks will help you with less water temperature fluctuations. As the weather starts to warm up this willassist keeping them longer. Smoothing out the daily temperature fluctuations in a system makes for healthier less stressed fish, and as such less chance of diseases becoming a problem. We have also found that shading a system with shade cloth in harsh weather conditions can also aid in controlling temperature fluctuations.

Rainbow Trout in Aquaponics SystemsThis year I have kept trout in my gravity fed Aquaponics system for approximately 7 months ( since 1 March till today 29 September 2012). Today the water temperature reached 22 degrees and there was nothing I could do to lower it so I decided that enough was enough and it was time to eat them. I had planned to grow them out a little longer however with the ever increasing spring temperatures its really difficult.

This decision didn’t come lightly and only after I added shade to the Aquaponics trout tank, additional airstones, insulation to the outside of the tanks and added ice to lower the water temperature.

If you decide to try trout remember that they are quite fast growing and if you get them at the end of summer its possible to grow them out to plate size before it gets too hot if you chill the water, have plenty of oxygen and have them in insulated tanks.

Trout prefer chilled water. It would be difficult to keep them in a tank without a chiller capable of bringing the water temp from ambient down to single digit figures. That said I have kept my trout successfully in water temperatures up as high as 15 degrees. After that they start to hover around the top of the tank and won’t do well.Time to Harvest Aquaponic Rainbow Trout

They need cool well oxygenated water and unless you live under a snowy mountains dam and had flow through system I would suggest that you will either need to eat them all like I did before summer. As the amount of oxygen water can hold is proportional to temperature I suggest you add a few air stones as the temperature rises.

As you can see in the photo my trout all grow at different levels. Although the trout were purchased as fingerlings, when harvesting its clear that they all grow at differnt growth rates even though they all have been kept in the same environmental conditions. I would have liked to grow my fish for another month if possible however my biggest fish were still plate size.

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