Backyard Aquaponics
A place to discuss aquaponics

Hey team, sad times at the moment.

About once a week for the past month I have noticed a silver perch sort of do its own thing, then die. They will swim near the top and not swim away when I put my hand near them like all the others do. They will do this for a day or so occasionally jumping up at the surface, I even saw one swim on its back the whole top of the water surface once. Then they will swim close to the bottom really slow for half a day or so, then sadly, they die. Lost 3, now another one is doing the same.

PH 6.8-7
Nitrite 0
Ammonia .25
Nitrates 160
Temp between 21-25

Very lowly stocked at the moment, and aeration is well and truly satisfactory. All fish look very healthy, then one just dies randomly

Any help appreciated, thanks

Very sorry to inform you all, but the silver perch mentioned above just died.

It has no obvious signs of any illness. Inside of gills are a normal pink colour. No other discolouration on the fish at all.

I'm quite insolable at the moment. I don't know what to do!
What if another one dies and I have done nothing to save its life?!

-K98

This does sometimes happen. It can be caused by lots of different things and that makes it difficult to figure out. In this case it sounds like the fish might have an internal infection based on your examination. You might want to salt the water to 1ppt (part per thousand) to help the fish with stress and help them build a slime coat. I'd also up the aeration even though it sounds adequate. (If you're growing strawberries salting to 1 part per thousand can kill them but most other plants will do OK)

Keep checking your water parameters as well - especially nitrite, ammonia, water temp and pH. If you're getting near the limits that your fish can tolerate you may see some die due to stress. It seems unlikely that anything is happening now but you may have had a spike a while back and the fish are just now giving in. Usually they'll have problems getting enough air and will come to the surface.

Thanks very much for your response Scotty. Appreciate it.

I had a friend take a close inspection of the latest dead fish and she noticed a 10mm red worm near the poop chute on the dead fish, as well as what looked like blood just under the skin surface at the base of the front fins.
Have looked up some silver perch specific literature and it's hard to ID exactly what condition the above symptoms relate to.

I isolated the fish tanks and salted to about 7ppm for 18hours then upped to just over 10ppm for about an hour before I started flushing with fresh water. Slowly flushing, down to about 5ppm at the moment. Will reduce to what I estimate is 3ppm before I link back up to grow beds. Bye bye strawberry plants!

Hoping this works!

Thanks again

-K98

Hiya Kiara, sorry to hear about the fish.
A description of fish stocks, sizes, tank size and grow bed volume will assist our attempts at diagnosing.
http://www.dpi.nsw.gov.au/__data/assets ... Manual.pdf
Here is a bit of reading for you.
Have you air in the tank? If not it's worth whacking some in. I wouldn't be feeding for a while either and as previously stated salt is your friend. Here is a good reason for two systems and utilising one as a hospital tank, strawberries in the other.
I run timed f&d and I will run the pump overnight occasionally if I feel a good tank flush is required. I've always hungry fish the next day. My API kit is out of date and run by feel now as they aren't trustworthy, how old are yours?
Hope things improve, good luck.

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Skeg In The Hills.

Hi Skegs!

I have read that PDF, and some of the symptoms matched up with the 'problems' outlined for silver perch. Ticked boxes for some, but nothing that really conclusively suggested one thing or another.

Yes, I have an airpump running full tilt at the moment. It is a Hopar pump, 10w, 4x3Lpm. It seems to create a lot of bubbles, would it be adequate?

System has a 2500L main tank, with an IBC sump and two grow beds, both ~800L of wet media. 6000Lph pump run 15min on 15min all day, then 15min every hour at night.

There are approximately 20 15-20cm silver perch and 50 little ones, about 5cm long and added about 6 weeks ago.
It has only been the original batch (the larger fish) that have been dying. The small ones do flash occasionally.
I froze the dead perch for further analysis later, and checked one of them today. It seemed to have blotchy colouring. Kind of white faded scales. Didn't look fungusy [sic] at all, but just a subtle off colouration. Have noticed some of the other deceased fished looked like they had darker colouration in areas too. I always figured it was normal for SP to have blotchy colouration, at least ever slightly anyway.

There is a fair amount of salt in the system now. Enough to just taste salty.

Good news is, one fish that was doing the pre-death ritual seems to have recovered... Or I can't find the body anyway?

Any advice/info always appreciated.

-K98

Hey Kiara

I’m not an expert as I’m newish to aquaponics and have only had experience with Kio and Goldfish.

Could it be possible that the fingering batch you introduced to the system 6 weeks ago may have caused contamination, a disease therefore affecting your mature batch of fish?

P.S. Sorry to hear about your fishies

_________________
Mike Napoli
vonapster231@gmail.com
Dianella, Perth, Western Australia

Hi Mike.

Umm, yes, the thought did cross my mind. I have purchased from this seller before, and from what I have read online he does seem to be one of the more reputable breeders in the Perth area.
I'm sure many people on here know him, and as such, I am not going to suggest that his stock contaminated my existing fish.
Of course it's a possibility though I suppose. Can't conclusively say that for a fact though, so I won't be passing the blame that way. Happy to take PMs if anyone wants to discuss that issue, however I won't openly discredit a seller online without any 'proof'.

Thanks for the thought though.

-K98

Very wise of you Kiara.

That shows great character and integrity!

Hope you get to the truth about what happened

_________________
Mike Napoli
vonapster231@gmail.com
Dianella, Perth, Western Australia

Reputable seller or not I always quarantine before adding to the main tank, it just makes sense.
Air and salt, which you seem to have, usually does the job.
Hopefully you are on top of the problem now and things get better.

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Skeg In The Hills.

Hope the salting helps Kiara. Mostly it is best to salt bath and quarantine in salt all new arrivals no matter what.
Even good suppliers can deliver something new to a system, so there is rarely a "good supplier = no issues" outcome.

Hopefully it is something simple that salting will address directly.

_________________
.
Darren ( dlf_perth )

May the fish sh*t and the plants grow.....

Jinx

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Skeg In The Hills.

That sucks Kiara. I have a similar problem.
Salt treatments have not worked for me. Killed my strawberries and that's about all it's done.

Does anyone know what kind of fish antibiotic is safe to use for AP?

No antibiotic is safe as far as I've read.
One of the things about salt treatments is that sometimes it's the salt shock that works so salting then waster changes then salting again can do the trick.

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Skeg In The Hills.

Ahh bugger. I had a read through the dpi disease guide link above and it mentioned something about Formalin?
Still not safe for fish destined for the plate?

Keen to hear from anyone who may have used anything other than salt... There must be something the aquaculture farms use, other than buying Bunnings out of salt.

Will give the salt shock another whirl and see how we go.

Thanks Skeg