Barramundi is a fast growing fish that can be grown successfully in backyard aquaponics, however in temperate regions the growing season is short and barely gives you enough time to grow them to plate size. Here is a tip to jump start your barramundi season.
It’s important to introduce barramundi fingerlings into your aquaponics system as early into the summer as you can, as you really only have a 6 month growing period before conditions become too cool. Whilst barramundi will survive into May, they will stop eating and actively growing. They become unhappy and will eventually become sick and die.
What a waste!
Also by running them too late into autumn you delay the start of the trout season (which is not to be missed!).
However getting in early and introducing them into water that is too cool is fraught with problems. They will stress, won’t feed, and generally make themselves susceptible to illness and disease.
The first few weeks are critical.
The timing of your introductions is dependent on the type of summer you are having, and each year is different.
Some years there is an early onset of warm weather and other years the warm weather doesn’t arrive until Christmas. An important consideration is night time temperatures when much of the heat built up during the day is lost to a chilly night. Large fluctuations in temperature between day and night also creates stress for your young barramundi, so it’s important that you time introductions based around consistently warm days and nights.
Remember one hot day doesn’t make a summer!
The ideal temperature for optimal growth and health is a warm 25 – 28 degrees, and its likely that the temperature in your system will not be within this idea range until mid-summer. This is far too late to grow your fish to an edible plate size, unless you buy advanced fingerlings that are already 20cm in length. Even in this case, you need your fish to ‘hit the water running’ and the secret is getting the water temperature as warm as you can.
Many people try aquarium heaters however these are largely ineffective and make a big impact on your household power bills.
As the photos suggests, the best way to get the water warm is with a pool solar blanket. Cut it out to the shape of your fish tank and put it on the water as soon as your trout have been harvested. Monitor the water temperature over the course of a few weeks and you will find that your water becomes suitable for barramundi weeks ahead of schedule.
Solar pool covers also double as an insulator at night and although you do still lose heat at night, the cooling isn’t as dramatic as without the cover. I keep the cover over my fish tank on over most of the summer and cut 50cm x 50cm square out of the cover that I can remove for feeding the fish. This has the added bonus of training the fish to know when dinner will be served and where it will be served.
This has worked well for me and I hope it helps you too.