Backyard Aquaponics
A place to discuss aquaponics

Hi, how many months will it take to grow trout fingerling to 500g?

Many people here have managed to grow 15 gram fingerlings delivered in March/April to 500+ grams buy November.

There will be many contributing factors to this but. For example:

Stocking level vs filtration
System maturity
Feed quality

These factors will dictate how much you can feed your trout and how often.

And of course your grow out season length

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And water temperature...

and size of FT..

... and weather and (allegedly) light (or the absence of it)

How long is a length of string?

The question should probably be...

I have 8 months of winter time in Melbourne, can I get trout to a reasonable size before a cull.

Replace the timeframe and location.

As long as they don't die in the middle of your 8 months they should get to a good size

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If you're careful, do the right things and have access to more trout in mid-winter, you could get two harvests in the winter and have a short summer with another species, for three harvest per year!

I tried to push the limits of winter in Perth; two harvests of trout was quite hard to achieve and nearly always I lost a few at the end of winter when we had a few early hot days. It's much easier to aim at one winter harvest and one summer harvest; but as Melbourne's climate is substantially cooler for a lot longer during the year you might not have as many weather-related issues?


Scott

and weather and (allegedly) light (or the absence of it)

What affect does light have on growth rates? Most FT's ive seen are covered, to reduce algee growth I would guess, and less stress on fish maybe, but didnt know this would make much diference

This summer was an exceptionally mild summer...

It would be a mistake to assume, or plan for 2 crops of trout... whether in Vic, Sa, Nsw, or WA....

Our normal summer temperatures just do not allow for it... unless you're prepared to invest in chilling your tanks...

The last 2 Melbourne summer would have been fine for trout....

Especially so that my fishtank is 1 metre inground....

Does melbourne have summers?

Thats a question I have been asking myself....horrible summers mean little to no plant growth.

There have been some recent discussions about trout growth rates in the presence of light, but not many studies concentrate on the absence of light.

http://www.backyardaquaponics.com/forum/viewtopic.php?p=329255#p329255

It wasn't over here in Perth.

It's been done before without cooling systems, but it can be a bit stressful!

If you can get trout (3-4 month grow out period) in by end of March, these can be ready by July (or as soon as the reach the target weight/size) and then straight in with the next lot which can be ready by end of October (if the weather doesn't warm up too soon). This becomes a little easier if you've got more than one tank or can separate the mature fish from the small; filtration dependent of course!

The risk: If the weather doesn't stay mild, particularly for the start of the first batch or the end of the second batch then you'll end up with a lot of dead small fish. The same can be said for trying to get the trout in too soon at the end of summer, even if you're only intending on one harvest; we had some cracking hot days in April and only now is it really starting to cool down. A few years ago we had a 40+ degree long weekend which came after two weeks of un-seasonally warm weather in September.

The safest option is to wait for the "real" end of summer before adding the trout and harvest at the first sign of summer approaching, and if you concentrate on only one harvest then you can have bigger fish at that time, but, two harvests can be achieved if you're vigilant and organised but not if you're inexperienced or under-prepared.

Be aware of risk; manage what can managed, mitigate against the rest.