Backyard Aquaponics
A place to discuss aquaponics

Hi :) I'm new to Aquaponics, fish and these kind of websites. I have Just finished building a system. I have two IBC tanks. one for fish and one for a sump tank. At the moment I have 4 x 125 litre growbeds (half barrels) but want to add to my system later. I have 5 large goldfish (about 10 - 15 cm) and about 40 small ones with another 50 coming once my system has cycled. I haven't added my goldfish to the system yet. I have added Ammonia and the nitrites are just starting to rise. I'm discovering I'm not very patient and have heard you can add Nitrifying bacteria to quicken the process. 1ST QUESTION: In New Zealand we have the API brand and I can get a product called quick start. But it sounds like it also takes away the nitrates which is what I want so is that the right product to use? The ones who sell it don't seem to know. 2nd question: I have also been told by a friend that goldfish need to have a small gravel or sand at the bottom of their tank but I have noticed that ones who breed them in the large ponds or who have them in aquaponics don't. Does this affect their health? Any help would be most appreciated. Thank you.

Welcome to aquaponics and a great forum. Many hours of fun and interest are ahead of you.

If you already have nitrites, I doubt you'll need to, or be able to do much to hurry the bacteria.

I have no experience with goldfish. but you're right! Plenty of people on this forum use them in aquaponics with good effect. I doubt you'll need to have gravel and it can be a problem in the bottom of a fish tank in aquaponics anyway!

I'm guessing that you will have about 400 L of wet media in your grow beds to start with. Rule of thumb many of us use suggests no more than 1 fish (to be grown to about 500 g) for each 25 to 30 L of wet media.

I know that goldfish are small but apparently they produce lots of waste. So maybe reconsider your final stocking density.

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Hi and welcome to the forum

Ive used goldfish a few times to start systems

Don't worry about speeding up the process you are almost there.

95 fish will overload your system to say the least so be prepared to rehome some when they grow as required

Feeding goldfish needs to be managed

Aquaculture feed that is commonly used to drive aquaponic systems is a bit hot for goldfish they can get too fat and get themselves in trouble .

Goldfish feed is next to useless as a nutrient base for your plants

So a bit of give and take and maybe a bit of nutrient supplements for the plants will be needed .

I lost some big goldfish once , they played in the splash from the growbed siphons coming back into the sump and lost scales and died so watch for that one .

Thanks Dave and Terra for replying. I'm not great at maths but I'll do my best to work that out. The tank that I'll be putting my Goldfish into only has a pipe going in for aerating the water. and one coming out for overflow into sump tank. I was considering putting the outflow from growbeds into fish tank to break surface water and create more oxygen but maybe I wont do that. 2 of the large gold fish are from my nephew and I'll be most unpopular if they die from losing scales! I just tested my water and it looks like my nitrates went up from 5 to 10 in one day. does that sound right? or maybe I did the first test wrong. I'm sure I got it right today with all the extra shaking of bottles and tubes. I'll take some pictures as soon as I figure out how to upload them.

As regards food for goldfish.... if I supplemented with a mixture of worms, mosquito larvae, and duck weed or peas. would that work for fish and plants? If I need to supplement a plant food could anyone recommend one. Would a liquid seaweed one be ok? thank you