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 Post subject: Comet goldfish deaths
PostPosted: Jun 28th, '17, 09:33 
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Location: Tillamook, Oregon, USA
Last year during the warm season I had quite a few comets die that were 1-2 year old fish. About 1-2 fish a week. They rarely had any visible physical symptoms and what they did have (a bit of red fin or unhealthy gil tissue) I chalked up to an accident that had led to elevated ammonia for a period of time. I think the last death was in around september or october. All winter long while the water was cool (50-60 F) and they weren't eating much I had no further deaths.

This spring, as water temps hit about 65 they started dying again at about 1-2 fish a week It affects the biggest the smallest, the oldest (3 years) and the youngest (3 months). It kills goldfish in two separate tanks in same system but it does not affect large mouth bass in third tank of same system.

System is 3x 600 gallon tanks, 1800g sump, and 24 4x4 IBC beds for a total volume of about 4500g.

I test PH (generally 7.5) ammonia nitrate nitrite and phosphourous are tested as well and are always pretty close to zero. KH is maintained between 2-4 with gypsum and limestone.

Water temp is currently 78, but I think it was only 68 when the first one keeled over this spring.

I have a hard time blaming anything other than a carp specific disease or parasite when the 1 year old LM Bass are completely unaffected as they are generally much less tolerant of water quality issues.

That said, the only physical symptom I can ever find is that the dead/dying fish are lethargic and generally not feeding for a few days before death, and very occasionally have a bit of red on a fin like you might see with ammonia issues..but the norm is that they appear 100 healthy..except the part where they are you know...dead.

Due to the coincidence with water temps, I had suspected KHV as a possible suspect, but they just don't show any of the major physical symptoms like I have read that they should.

"The main signs of fish infected with KHV include weakness, lethargy, loss of equilibrium, inappetence, erratic swimming, sunken eyes, "notch" in the snout of the fish, excessive mucous production, increased respiratory rate, discoloration, and hemorrhagic lesions on the skin and gills"

Anyone have any thoughts or experience that may help me diagnose these poor fellows? there are a lot of months of summer left and I really don't want to loose that many more fish!

Thanks,
Rhythm


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PostPosted: Jun 28th, '17, 15:04 
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In the winter time with cooler temps you have better oxygenation and the ammonia that's present is less of a problem. You also would likely have less algae to use up oxygen and cause pH fluctuations. Going along with this you'll be feeding more in the summer because of the warmer water temps.

You may be seeing the effects of an infection but it also sounds a lot like what you'd get from an ammonia or nitrite spike. At the pH and Temp you have it wouldn't take much of a spike.

http://ibcofaquaponics.com/information/tables-and-charts/

You haven't mentioned how many lbs of fish are in your system or the filtration?


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PostPosted: Jun 29th, '17, 01:30 
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Ammonia, Nitrate, Nitrite and Phosphorous always reads zero on the API test kits. Water is clear, and algae is minimal - all water is covered by rafts, shadecloth, or gravel except a 2x4 rectangle over the pump.

Filtration is the 24 4x4 IBC media beds (scoria and expanded shale). System is in a greenhouse, it's flood and drain beds with rafts on the sump and 3 constant height fish tanks. It's 3 years old now and definitely not a cycling issue.

Between all the media beds, and the 5kgph pump dropping water into the tanks oxygenation should be good. When the rafts are running full I run an air bubbler system under them for extra oxy but rafts are mostly empty right now. Haven't weighed fish in a while but the combined weight is probably only about 25-35 lbs now.

If it was a water quality or oxygenation issue those bass *should* be having issues long before the goldfish and yet they are perfectly fine.

I bred the goldfish in the spring before they started dropping, and the fingerlings also started dying about a week after they were added to the system, scooped out 4 more this morning.


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