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We have a 500 gallon tank with about 100 fingerling catfish. The ammonia is in the harmful to dangerous range (I don't have a more specific measuring test). We have lost about 10 or so fish. They are not eating and they surface for air. We have a 4 station aerator driven and have a constantly cycling system. The pH out of the borehole well is about 7 to 7.5. We have added significant amounts of nitrifying bacteria starter but register no nitrites or nitrates. Water temp is a little cool at 65 deg. F. Yesterday we drained the tank to about 100 gallons and refilled to about 300 gallons exchanging some of the water as we went. The ammonia level was better but not great. Is there any natural source of nitrifying bacteria that will help us get the ammonia breaking down? I am in Nigeria, so I don't have access to all the nice commercial stuff and we want villagers to be able to manage a system with locally available resources. If you can't tell we are pretty raw at this and the system is only about 2 weeks old.

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You need a test kit, or some way to measure the ammonia... and the water temperature...

 

There is a relationship between pH, temperature... and the toxicity of ammonia....

 

Don't add ANYTHING else to your tank.... and DONT FEED....

 

Do another 50% water change to bring the ammonia down further, and make sure you have plenty of aeration and pumping...

 

What sort of filtration do you have??

 

100 Catfish in a 500 gallon tank is well and truely pushing the upper limits... even with a large amount of filtration

Yep, as Rupe says.

 

Your system is still too young to really easily support such a heavy fish load even if it is operating well.  It generally takes about 6 weeks min to cycle up with fish.  It is generally recommended to start with a small amount of fish to start rather than the whole max load.

 

Now if your catfish are small fingerlings, a 500 gallon tank with an appropriate amount of filtration that is already cycled up could handle them at least for a time but you are dealing with a not yet cycled up system and so you are struggling with your fish load and trying to cycle up at the same time.

 

If you intend to grow out catfish the way I do, I would recommend only 50 fish but then I grow them big.

 

Yes, we need to know how much filtration you have for those 500 gallons of fish tank.

Catfish fingerling are very sensitive to ammonia. If they are not swimming and gasping they have burned their gills. Your die off over the next week will be massive. Sorry about that rough start. Really not much you can do but what the above have told you. Keep your chin up and buy 30 next time and start again.
Thanks to all. We knew we were starting too aggressively...I was wondering if anyone knows of a natural way to introduce nitrifying bacteria, not that the store bought stuff is not natural, but I don't have a store to buy it from. The system runs all the time pretty much (we are losing about 3 hours of cycle in the early am because the solar/battery system needs to be adjusted). It cycles water from the tank to a bucket filter that has a filtering material ( a tight fiberglass filter mesh). The water is fed from the bottom of the bucket and out through holes above the filter. The bucket is at the head of the growing bed which is filled with about 4 " of granite chips for gravel. The bed is 24 ft. x 4 ft.x 8" deep, approximately. I have some lettuce in it, a few tomatoes, peas and cucumbers. Not much since the nutrients aren't really there yet. We'll keep struggling to get it adjusted, thanks for the encouragement.

Brian, the bacteria you need are everywhere in nature. They come just by starting a system and getting some ammonia in there from fish or any other source. You don't need to add anything else EXCEPT about 6 weeks of time.(Maybe even 8 weeks, changing water slows it down)  The stuff you buy at the store can help it go a little faster but it still takes time. 

 

Thanks that helps a lot. Patience is not always a luxury here but we'll dig in and see what happens. 

Richard Wyman said:

Brian, the bacteria you need are everywhere in nature. They come just by starting a system and getting some ammonia in there from fish or any other source. You don't need to add anything else EXCEPT about 6 weeks of time.(Maybe even 8 weeks, changing water slows it down)  The stuff you buy at the store can help it go a little faster but it still takes time. 

 

If you have a worm bin, a hand full of nice worm castings into the gravel grow beds along with some worms can help things along but cycling still usually takes about six weeks if you add something and it takes about half a dozen weeks even if you don't add any bacteria booster.
So what you're saying is six weeks...Thanks. What would be the purpose of having a worm bin? Haven't really seen that mentioned anywhere. 

TCLynx said:
If you have a worm bin, a hand full of nice worm castings into the gravel grow beds along with some worms can help things along but cycling still usually takes about six weeks if you add something and it takes about half a dozen weeks even if you don't add any bacteria booster.

Worm bins for worm composting "Worms Eat My Garbage"  Worm castings or "worm poop" is great for the garden and generally contains a great amount of beneficial soil bacteria.  This can provide the startup bacteria for the nitrogen cycle in aquaponics and many people have found that worms in the grow beds help in keeping the grow beds from becoming clogged with fish poo and old plant roots.

Well Brian welcome to AP on the fly. It sounds like your humanitarian opportunity has yielded a lot of life lessons and some good advice. I'm curious now were you able to save Any of the catfish or was the whole thing a flop? "most people miss opportunity because it is dressed in overalls and looks like work"
You might be able to use some activated carbon to remove some of the ammonia in the mean time. You should be able to source it locally.

As stated in the good advice above, do water exchanges and DO NOT feed the fish. Remove dead fish immediately, as they are a rich source of still more ammonia if they decompose in your system. Also, make sure there is no algae growing in your system (fish tanks only, now, I suppose?). Remember, the nitrifying bacteria are photo-sensitive, and UV will kill them off. So, cover your tanks, and your troughs, if you have them built already.

Richard is right, the nitrifying bacteria are ubitquitous, and will colonize your system over time, but not until the ammonia drops below 3.0. However, based upon our own experience here at Friendly Aquaponics in starting over 15 systems over the past four years, we have had excellent success starting systems in only 3-4 days with the bottled nitrifying bacteria from the AES catalog, but I understand you can't get that. It's a total waste of money anyway, if your ammonia level is over 3.0.

So, waiting and water exhanges are you only option. Best of luck, and please tell us how it goes!

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