Koi dying! IBC setup

SouthWalesFish

Hi all,
I’m a newbie and am feeling terrible as I’ve lost 5 fish in the last 3 days.

My setup is:
~800 Ltr tank
2 1m2 growbeds with a few plants

10 4” grass carp
10 3” koi carp

2 air pumps

Testing 0 for nitrates/nitrites. Ph ok etc.

Temp is around 15 deg c at moment. I realise the stocking density is very low so thought I’d have more leeway.

Fish aren’t feeding well and seeming lethargic. Can’t see any obvious signs of disease...

Any help appreciated!

I’ll try to attach pic of last one that died.

arbe

What is your pH and ammonia reading?

If they aren't feeding well I'd suggest withholding feed for a while.

Can you see the remaining 15 fish or could one be dead hidding somewhere?

Terra

I feel for you

Losing fish is no fun most of us have had experience of that

My first thought is could have been a nitrite spike a few days ago which may have done some damage.

As Arbe posted a ammonia reading would help

And yes no more feed until problem resolved

This feed thing has been a hard one for me ive had livestock (farmer) all my life and getting my head around fish can go a long time between feeds without losing weight has been difficult .

Over feeding is high up there on the mistakes list for all of us

How many litres of WET growbed media do you have

Best to start with at least 20 Litres of wet media per fish

Is there any fish waste / uneaten feed in your tank

And how old is system , there is so much going on in the beginning its best to cycle a system with no fish .

Even when a system has "Cycled" it doesn't mean its capable of full capacity the bacteria breed and there is a lag time for this , so a new system has to be watched carefully .

SouthWalesFish

Thanks all!

I had more Koi dining (not the grass carp for some reason( so I’ve missed bed then all and drained the system.

The ammonia was low but There could have been a spike and there was some uneaten food around for a while.

Some other factors that might have been an issue - man I have a lot to learn!...

- I was feeding the carp weed taken from my large outdoor pond so I guess lots of unknown stuff could have come in on this.

- temp has been quite low at night and warm in day so maybe temp fluctuations a problem

- I possibly rushed the cycling in excitement...!

Hmmm.

dlf_perth

>> I realise the stocking density is very low so thought I’d have more leeway.
>> 10 4” grass carp
>> 10 3” koi carp

20 fish is not low stocking, not as bad as some newbies with 30-50.....
20 is pretty much a full stocking for a 800L tank until you have the system matured.
You definitely wouldn't want more than this in a new system IMO.

Low stocking is more like 10 fish. Very low would be 5 ;-)

Most likely ammonia though feeding the fish pondweed can have a high risk of introducing something.
Fish are very sensitive to that sort of thing, particularly when stressed which new fish in a new system will be.

>> and there was some uneaten food around for a while

bacteria is also an issue in colder water - but not usually an early problem.
(unless circulation or filtering is poor - show some pictures of your system)
You don't have a sponge over your pump inlet do you ?

Stay with stuff you purpose grow or else commercial feed.

>> 2 1m2 growbeds with a few plants

how deep are your grow beds, and have you used anything for the plants ?
what type of media.

what is your water source ?

how to post pictures > viewforum.php?f=4

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