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I finally got my fish. 30 Bluegill and 10 channel cats. They have been in the tank for 24 hours now with no apparent issues. The catfish started eating immediately after release and the Bluegill were eating after a few minutes. Both groups were very busy swimming and didn't seem to have a preference of water depth. 


Today the BG are still eating very well but the catfish have become reclusive. Did some water checks to make sure everything is in spec.


  • PH 7.4-7.6
  • Temp 76 F
  • Ammonia 0 PPM
  • Nitrites 0PPM
  • Nitrates 80- 160 ppm (worrisome)

Been doing small water changes to decrease nitrate level and putting in more plants. How long before the high level effects the fish?


There should be plenty of Oxygen because I have added an Eco 4 air pump with the air stones distributed around the tank where there are no water returns. There are 6 different returns that keep the water surface fairly agitated. 


Any advice will be appreciated.

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Comment by Wayne on June 13, 2011 at 7:36pm

Found 1 Bluegill floating this morning, had his tail missing, then at mid day found 2 catfish dead.

All the test readings were the same with the exception of the nitrates. Nitrates have come down to between 40 & 80.

Catfish are still not showing up at feeding time but the larger pellets that the bluegill can't eat have all disappeared from the tank. The only feed that the hardware store carries is the Purina game fish brand. It has 5 different sizes that I pick through to get only the smaller pieces.


No casualties this evening and the Bluegill are more aggressive at feeding time. I just wish I could see the catfish eat a little.

Hopefully tomorrow will be a better day.  

Comment by TCLynx on June 11, 2011 at 10:43am

I might recommend trying a "dilution" check on the nitrates just so you can be more certain how accurate your reading of the level is.  (I personally have trouble telling anything over about 35 ppm on the nitrate test.)  So you could put say 1 part system water into a measuring cup and then 9 parts plain water that has not nitrates (my tap water generally tests out at 0 nitrates so I use it for a dilution test but if you are in an agricultural area where the wells are higher in nitrates you might want to run the test with some distilled water.)  So you mix up 9 parts plain water with 1 part system water and then run the test on that and times the result by 10 to get your reading.


Now that is just for piece of mind and I only do it occasionally.  My big system has grown plenty of channel catfish and I've had nitrates up over 80 or even 160 for whole seasons (during summer here the fish eat a lot but it is so hot that many of the veggies actually slow way down on using up the nitrates unless I'm growing excess bananas.)  As far as I can tell high nitrates are not that big a deal to channel catfish.  I think they gotta be up over 400 before they are of real concern unless you are raising breeding stock.


That said, definitely get more plants in.  And constant water changes may actually be making it harder for the plants you do have to use up the nitrates since it is common for source water to have a high pH and the higher the pH the harder it is for the plants to get everything they need in the right balance.

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