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ericheeg
10-31-2011, 01:47 PM
i have about 50 catfish fingerlings in a 300 gallon tank. they were veracious eaters until a week and a half ago. now they won't eat floating food at all. I am using a biofilter and also forcing other return water @ pretty high pressure to increase oxygen until i get an aerator. i have had the fish for about a month. any help would be graciously appreciated!

LowCarbTNPer
10-31-2011, 03:25 PM
What are your water parameters? (pH/ammonia/nitrite/nitrate)

If you are in an area that is getting cold it may also just be the lower temps causing them to feed less.

foodchain
10-31-2011, 03:54 PM
What are the fish physically doing? Watch the fish, how they are acting gives you clues too.
Based on the info you provided, I would suggest changing out about 20-30% of their water for fresh water that has had the chlorine removed.
Most likely this is a water paramter issue. If they have been eating like crazy, it also means they are pooping like crazy. What kind of cats do you have? Some are more aggressive than others.
A water change, not all the water as this will shock them, will temporarily solve your symptoms. BUT it's not a fix. Just a band aid. Give me some more info, and I can get you better answers.
Good luck.

cedarswamp
10-31-2011, 06:03 PM
Where ya at? Has your water temp dropped lately? Cats will survive cold water but they ain't gonna eat much.

keith_r
10-31-2011, 08:04 PM
some catfish aren't wild about a high "flow" too...
as others have noted..
what have your temps been.. and what are your water parameters, ph, nitrites and nitrates.. what kind of "pond filter? what's it rated for?

urbanfarmer
10-31-2011, 08:24 PM
What are your water parameters? (pH/ammonia/nitrite/nitrate)

If you are in an area that is getting cold it may also just be the lower temps causing them to feed less.

Barring any disease or highly unusual environmental factor, your answer lies in the above questioning (excluding nitrate).

keith_r
11-01-2011, 06:03 AM
i know uf does not agree...
but i read elsewhere that while many fish are ok with high nitrAtes, catfish can have problems.. especially when fingerlings.. i'll try to search for it today, but it's gonna be a busy one at work

foodchain
11-01-2011, 07:18 AM
It's been my experience, not sure about others....that fingerlings are more sensitive to most out of whack parameters. I don't find this specific to species. Not sure if it's due to size, making them more sensitive, or if it's a maturity issue, or what have you. But when I take semi adults/adults and expose them to the same stresses as fingerlings or even juevies the younger always shows stress and ailments long before the adults. Especially true with amonia, and DO issues for instance when a pump burns out, or I over stock, transport, etc. I do believe though, that changing a considerable amount of the water will help. There's a quote I saw somewhere of "stop polution through dilloution" Or something like that. And I have found this to be very helpfull. Does anyone else have experience in this?

stucco
11-01-2011, 08:20 AM
My catfish (channels) stress if I don’t keep the tank covered and won’t eat. When I get new fingerlings I feed through a small opening in the cover until they get used to things.

urbanfarmer
11-01-2011, 09:18 AM
i know uf does not agree...
but i read elsewhere that while many fish are ok with high nitrAtes, catfish can have problems.. especially when fingerlings.. i'll try to search for it today, but it's gonna be a busy one at work
Oh, I wasn't commenting on if nitrate toxicity exists in this particular fish species... I was just trying to keep it simple because in aquaponic systems nitrates are relatively low (under 100 ppm, often under 40 ppm or some people have near 0 ppm). Save the poor guy a test and confusing anyone else that might be trying to help. I am now in a more "hands off" mode. I'm passing the torch to you keith!!! :mrgreen:

Your test should read the TAN (total ammoniacal nitrogen), which is NH3/NH4 combined. NH4 speciation is associated with pH (I may be stating the obvious for some).

NH3 - unionized ammonia or just ammonia (toxic)
NH4 - ammonium (non-toxic)
NO2 - nitrite (toxic)
NO3 - nitrate (non-toxic or weakly toxic depending on species and stage in life cycle)

DISCLAIMER: And yes, I know speciation occurs for the other chemicals too and more speciation than listed also occurs, but this is the bulk of the relevant and significant interactions with the nitrogenous compounds.

ericheeg
11-01-2011, 10:49 AM
thank you to everyone who has posted some help. i tested the water with some test strips by Jungle Labs. it reads:
nitrate: 0-20 ppm
nitrite: 1.0-3.0 ppm
hardness: 75-150 ppm
total alkalinity: 180 ppm
pH: 7.2

the tank is in a fairly climate controlled classroom so i don't think temperature change would be the culprit.
they're behavior is pretty stressed. some are suspending toward the top, some are awkwardly & slowly swimming. when they were healthy, they were laying at the bottom.
the filter is made by tetra and was built for koi ponds. it is rated for up to 1000 gallons i believe.
they are channell cats.
i plan to replace about 100 gallons of water today. it won't be declorinated, but i have some bait-saver additive that has worked when i had to add water do to evaporation.

keith_r
11-01-2011, 11:01 AM
nitrites are bad.. usually folks "salt" their tanks to help the fish deal with it..
does your water have chlorine/chloramines? if not, a water change of 50% would reduce nitrates,
i'd try salting to 2ppt to help the fish deal with possible "brown blood disease"

urbanfarmer
11-01-2011, 07:01 PM
I agree. Having a 3 ppm Nitrite concentration, and assuming it could be higher with that kind of cheap test... coupled with the fact catfish seem to be fairly sensitive to nitrite compared to other cultured species... well, I would definitely pin that as the cause. Try the water change keith suggested.

Full article free (but old): http://ciresweb.colorado.edu/limnology/ ... Pub079.pdf (http://ciresweb.colorado.edu/limnology/pubs/pdfs/Pub079.pdf)

and...


The 96-h median lethal concentrations of nitrite to channel catfish (Ictalurus punctatus), tilapia (Tilapia aurea), and largemouth bass (Micropterus salmoides) under similar water quality conditions were 7.1?±?1.9, 16.2?±?2.3, and 140.2?±?8.1?mg NO2-N/L (mean ± SE), respectively

In layman's terms, that's saying they die in FOUR days at 7 ppm nitrite.