Introducing Fingerlings into Aquaponics

Getting fish for your new aquaponics system is fairly easy to do online in Australia. I’m sure the process is similar in your country too. You need to track down a hatchery in your state or country. Some US states have very strict rules about what sort of fish you can grow at home. Tilapia are the main species grown in the US.

Here in Australia Tilapia are outlawed so do read up on your state regulations. We are pretty relaxed here in Queensland Australia about taxing people with fish licensing rules. We got this batch of 50 Jade Perch fingerlings from a Hatchery in Queensland. Cost me around $100 including the delivery fee. The fish will arrive by courier right to your front door overnight. Do not throw the polystyrene box that the fish come in away as it will make an excellent chicken egg incubator down the track if you are so inclined! That’s my next project (!)

The plastic bag that you find inside the box is full of injected oxygen. Fish will die quickly if they have no dissolved oxygen. I can’t stress this enough as it’s their lifeblood and you must have provisions in place to aerate their home or you will lose the whole batch very quickly. The simplest way is to have a cheap aquarium 4 line aerator hooked to a set of stones that will create bubbles in the water.

Aeration is a whole chapter we could talk about in detail. Most people think it’s the little bubbles that you see in an aquarium that are dissolving into the water and adding oxygen into the fish tank. I was assured recently that this is not true and a common myth by a biologist. Dr Wilson Lennard an expert on Aquaponics who says that it’s the breaking of the surface tension at the surface of the water body that the bubbles release Co2 into the atmosphere as it takes in O2 in it’s place. Most people find this hard to believe. Wind and waves in a large body of water do the same thing. A paddle wheel disturbing the surface of your fish tank will aerate your tank. Rain falling into your tank will add some oxygen as well. Break the surface tension and you are in business with raising fish! Never forget that rule.

So we take the bag out and unseal it and place the entire thing in your new home – our aquaponics fish tank. The oxygen comes rushing out. There’s an ozone smell about it. I like to get some cloths pegs and keep the bag in the water in case it floats away. The idea is to get the temperature of the bag to meet the same temperature of the fish tank. I also throw in an airline to keep the oxygen supplied to the fish. Sudden shocks will kill fish. Apart from no oxygen – the next big killer of fish is Stress! These little fish have come in a bag, knocked about by travel, sloshing about in the back of the van and have probably been purged of feed for a few days so that they don’t literally vomit in your bag! The fish are small. They are sensitive little babies. At around 4cm in length they are very vulnerable, so it doesn’t take much to crush them when you lift the bag.

Next I like to slowly mix some fish tank water in with the water in the bag. Its important to know the pH of your fish tank water and the pH of the water in the bag. If you are serious about Aquaponics you must test your water regularly. Its important for growing fish and its important for growing vegetables. Fortunately as your system matures, it gains more stability and you can relax a bit after a few months. So a few litres of water are introduced over the course of half an hour or until you feel the water and pH in the bag is close to your main tank water.

Now because we have some very large Barramundi and mature Jade Perch in this tank – we have a problem. There is nothing more the larger fish would enjoy eating more than a feed of these little babies! So it’s important to separate them until they are a few inches long and able to take care of themselves.

That’s where our nursery tank comes into its own. This plastic tank is nothing more than a plastic laundry basket that you can get at any hardware store. I have lined the inside with some fly screen mesh. We got this idea from Murray Hallam’s Aquaponics Secrets DVD and it works exceptionally well! But be careful. Fish are smart and Murray later mentioned to me that these little fish will figure out a way to get out of this laundry basket by swimming sideways to squeeze out of the tank through the gaps in the slats! Don’t use a wire waste paper basket as a fingerling basket! I did and had baby fish garrote themselves by sticking their heads through the mesh! You want a fine mesh to separate the fish from the larger fish outside.

When the pH and water temps are balanced, all you need to do is pour the fish into the laundry basket and start feeding them.The photos on this page were taken yesterday. Fish are all doing well today except for one mortality. In 12 months time – they in turn will be consumed having provided the energy to grow our vegetables for the year.

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