Backyard Aquaponics
A place to discuss aquaponics

Hi all my name is Mike Napoli and have just purchased a little system for leafly greens and herbs. I'm in the process of starting the nitrogen cycle so I've planted some seedlings but won't introduce fish for another week or two. Placed a raw prawn in system to start the release of ammonia.
My fish tank is approximately 300 litres and my choice of fish is going to be Kio. A question I have is how many kio would you guys recommend? I was thinking 10 to 15 fish....any thoughts would be most welcomed!

The amount of fish will depend on the size of your growbed.

Hi Arbe thanks for your reply!

I placed roughly 100 litres of expanded clay into media bed. The surface area is 0.6 square metres and the volume is 0.108 cube metres.

Does the volume of plants grown in the grow bed effect fish stocks and feeding patterns due to more nutrients required to keep plants happy?

The normal ratio aimed for in regards to growbed volume to fish is between 25litres:1fish and 20litres:1fish so with 100 litres of growbed you are looking at a stocking density of 4-5 fish.

Is 4 to 5 fish for species like your silver and jade perch, trout and barramundi etc?

I was going to get kio or gold fish....will that still apply ArBe?

It is and will depend on what you feed your fish. A good feed will cause your fish to grow large and provide nutrients for your plants.

Koi can grow large. I don't have much experience with Gold Fish.

Thanks for your advice ArBe!

I think I will get 5 to start with and monitor ammonia, nitrites and nitrates until system has stabilised.

That's a good idea.

Start off slow, have no issues and enjoy a beer/whisky/wine with your system.

Arbe has given good advice. Koi are a high waste fish, I've seen it recommended in aquaria circles 1 koi per 1000 litres although I'm sure it would depend on the size of fish.
I've had problems with koi so make sure you give them a good salt bath before adding them to your system. What are you planning to feed them and do you have a water test kit?

Yep I've got a water test kit. I've placed a raw prawn in the system two days ago to produce some ammonia to get the nitrogen cycle started and testing water every day to check levels. Haven't checked for nitrite or nitrates yet but will check tomorrow to see if any bacteria is present.

The food I'm going to start with is fry crumble made by Ridley which has a very high protein percentage around 50% so I'll have to be careful how much I feed them.

Skeg you mentioned putting fish in a salt bath before introducing them into the system. May I ask how one would go about doing this? Also where do you purchase your fish from as I'm in Perth also?

Who is giving out this advice about cycling a system with a rotting prawn Mike?... It comes up every few months on the forum and I cringe every time I hear it. The rotting prawn risks introducing disease into the system.

Just one example... If you've ever seen uneaten fish feed pellets that have been laying on the floor of a tank or pond rotting for a few days and ended up with a white fungus growing on them, that fungus can actually transfer to live fish.

Another example... I used to have a few tanks at the back of my store where I bred yabbies for a farmer to stock his dams with juvenile males. Everything went swimmingly for a couple of years while I was feeding them on peas, carrot, fish pellets etc, but at one point I fed the breeders with river prawns cut into small pieces. Within a few days I started losing the youngsters and the female breeders started dropping their eggs, in the end I lost every youngster. Even after draining, cleaning and sterilising the tanks, and treating the breeders with salt baths, I couldn't get rid of whatever it was that was in there and we stopped trying to breed them here.

I would remove the prawn a.s.a.p. and use Seasol Powerfeed to cycle your system. Add a capful per day and test the Ammonia level 24hrs later, repeat each day until you get the Ammonia level to somewhere between 1.0ppm - 2.0ppm. Your system isn't cycled until The Ammonia and the corresponding Nitrite spike have both dropped to 0.0ppm, at this time of year here in Perth it would probably take at least 3 weeks, but could take 4 or 5.

The Seasol Powerfeed will not only add the Ammonia required for the cycling process, but will also provide nutrients to get your seedlings started.

Where in Perth are you Mike?
If you are close you could get some water from our tank which is running for nearly 2 years now.

Also, koi are getting big. I have 6 koi in our 1500 liter tank and that's much already. Especially with the bigger two koi's being over 50 cm long.

Hi Wilsil



That's very kind of you to offer....I'm in Dianella

Wow that is some big fish....I only have a small fish tank (300 litres).

May I ask where you purchased your kio from? I want to get some butterfly kio for my system!

Wow thanks for that insightful advice Mr Damage.

It didn't cross my mind the prawn could potentially cause contamination and disease into the system.....I got that prawn out quick smart!

May I ask a few more questions:

Will I need to do a water change? Plus you mentioned sterilising your system, how do you go about that if required?

Do you recommend giving the fish a salt bath treatment before placing them into tank? What procedure do you use when giving this treatment to the fish?

You mentioned that the ammonia levels will spike at 1 to 2 ppm. Is that the same values for nitrites?

Last one, would you recommend me holding off putting fish in my tank until the spikes have dissipated and system is stable and cycling correctly?

Once again thank you for your help!!

I'm sorry to here about your yabbies.....must have been devastating!

Mike