Backyard Aquaponics
A place to discuss aquaponics

looks like a bacterial infection to me Matthew.

according to my aquaculture book:

"The disease manifests as an acute gastrointestinal septicemia with rapid mortality or as a chronic form characterized by an ulcerative lesion on the top of the head, which may proceed to septicemia and death".

i hate to say it but you may need to destroy the remainder of the fish, sterilize everything and start again with disease free stock.

i hope this is not the case and it was due to environment rather then disease.

good luck.

Whoow a bit drastic, there BF.
If the fish are going to die because of what you have said.
Then signs will start to emerge(sp?).
Beyond spieces specific!
I would be trying the suggestions first.
Then if deaths continue to occur you may consider yr suggestions.
algal growth is simptom from several possible causes.
Don't panic.

Hoping (for your sake) it's not this .... Columnaris

Bit about the "saddle" appearance riased my eyebrows....

Check out their mouths and fin areas

Edited :

Mathew.... what sort of catfish are they exactly?

your right c1. i was being a bit drastic.

what i meant to say was i wouldn't add any more fish until what ever it is gets controlled. who knows how long that will take though. even if you do get it under control, i would be concerned about adding more stock to the system in case of further infection.

what ever you do good luck to you Matthew.

Heres a couple of websites that may give you an idea...

http://www.disease-watch.com/documents/ ... 025ccv.htm
http://aquanic.org/publicat/usda_rac/ef ... 4702fs.pdf
http://www.aquaflor-usa.com/secondary/f ... isease.htm This is a good read!!

Has the temperature of the water increased or decreased recently. Look at all the factors... If it is a disease, have you introduced anything into the system, even plants. Something must have triggered the deaths.

EDIT... This could be it: http://msucares.com/pubs/infosheets/is1392.htm

OR these:

http://freshaquarium.about.com/cs/disea ... mnaris.htm
http://govdocs.aquake.org/cgi/reprint/2 ... 270050.pdf

I think that you should take these steps: 30% water change, siphon all the gunk on the bottom of the tank, remove any affected fish to a hospital tank (or cull them), then dose the tank with at least 3ppt salt.

Good ideas Tim..... except for the 30% water change......

Probably be hard to do with a 60,000ltr swimming pool

Yeah... would be a bit hard... Plus how much salt would you need?

60 * 3 = lots of salt

I gave you the benefit of the doubt on that one Tim

Thought you meant dose the "hospital" tank with salt

if the water needs to be dumped its one hell of a learning curve. makes me realize i need to think hard about my swimming pool system. perhaps a uv sterilizer would be worth a shot but more $.

Can you hire them BF? Or make them?

Check ebay

or F&F's local tip :-)

Still think it's just ammonia toxicity. The pH is ranging wildly, and goes quite high. Ammonia just hit 1.0, the temps are high, and catfish are probably most susceptible since they have no scales.

See the chart.