Pond Boss Forums GENERAL QUESTIONS Water chemistry Low D.O event?

I think I may be having a low dissolved oxygen event. It was dark cloudy and windless the past two days after a hot sunny spell. We got a cold 1.1" rain yesterday. Fish fed well yesterday morning, not so much yesterday evening. This morning, I noticed almost all the CC and BG gathered in about 10" of water along the banks. No dead fish or piping fish. The FA appears to be dying and sinking. I don't have aeration, but I started pumping in fresh water from my intermittent flow creek along the surface almost parallel to the bank at 9:30 this morning. I am still pumping an hour and a half later, and the BG have moved away from the banks and the CC are moving around more now. Am I doing the right thing? I could pump most of the day if the creek has enough flow. Supposed to get sunny this afternoon, but only 6 MPH breeze. I don't have electricity there to aerate, only a gasoline powered 2" pump that puts in about 3,800 GPH.

1/4 acre pond 11 feet deep. Good sun and wind exposure. Visibility today about 16 inches. Greenish water. Water has cleared considerably since Saturday.

Edit: 3:00 PM. Still pumping. Bluegill behavior has almost returned to normal. CC still in shallows but have moved to about two feet of water and are swimming around some in current coming out of pipe.

John,
Is the water you are adding flying through the air or is it being directly added. The reason I ask is because if the water travels through the air in a spray it will be oxygenated. If the water is just added in a column, it will only pick up a small percentage of the O2 it could have had it been sprayed.

18 to 24 inches of travel through air exposure equals saturation for water. It happens that fast, but it needs to be exposed to the air, so spray baby, spray.

It's creek water. The pump picks it up a little way downstream from a waterfall. As it runs into the pond, it enters a floating corrugated pipe and flows for about 8 feet before exiting into the pond in a stream of bubbles. Bluegill behavior has completely returned to normal. Hordes of them will come after a grasshopper thrown into the water. CC are still shallow but moving around more, no longer staying relatively still in shallow water. The sun is out and there is a breeze on the water. Going to pump all day if I can. Already added about 23,000 gallons of well oxygenated creek water.

Edit 8:40 PM: Planning to pump creek water until about 10 PM. That will be over 45,000 gallons of new water added today, nine vertical inches added and still about four inches below the spillway. Tested BG with a handful of food; they fed normally. CC moving around well, not feeding, but circling under the BG food.
Hopefully, we will make it OK through the rest of the night. It's supposed to be clear and mid 80's tomorrow, so plankton should make lots of oxygen.

Planning to back off on feeding for a while, and take out some CC for food.

Everything seems normal this morning. Fed sparingly only to test response. No dead or distressed fish seen.

Good update, glad things are going in the right direction.

Glad to hear things are ok John.

I thought a while back when you talked about the amount of feed you were feeding you were pushing growth pretty hard.

If it was a low DO event, your plan of action sounds like a good one.

Pond seems to still be clearing. Going to set up the pump on the dock and do some shallow water circulation early this evening. No wind again today. Also, I need to remove some more CC. Only ate five so far.

I pushed growth as hard as I could; the CC are all eating size and larger now. I am now going to back off on feed for CC and BG. There are hordes of small BG now attacking the Optimal BG Jr. The CC need to eat some BG.

BTW, last time we fished for CC we had two break-offs on the 1/64 oz barbless jigs on six pound test. Going to need to use heavier tackle. Some of those are near five pound brutes at only two years of age.

Edit: Here's a picture of pump recirculating. Ran this evening over 90 minutes and got a good current going around the perimeter of the pond. The suction line was about two feet under water.

Found one dead CC this morning, about 17". No other dead or distressed fish seen. I hope this event is over for now. Edit: Now two dead, second found around noon, still fresh, eyes not clouded yet, not stiff, but gills just pink, had died just minutes before. No others found as of about 4:30 PM.

Edit: Thurs June 22 - no more dead fish found. Threw out small amount of food this morning; CC ate it right away. Going to try to fish them out late this afternoon.

Update: We caught 4 CC weighing a total of 12 lbs 9 oz. The largest was 5 pounds even with a length of 22-1/2 inches. Pretty good for only two years old.

As of this morning I have harvested out a little over 19 pounds of CC since the Low DO event. How much harvest should it take to make my DO stay relatively good? Probably still at least 55 large CC in my 1/4 acre in my estimation average about 2.75 to 3 pounds. Plus lots of BG.

That is a good harvest size. I think I would store them in the freezer instead of the pond. Take out all you can. Give room for your remaining fish to have good water quality and room to grow for the heat of the summer.

Wish we had some heat up here. 60 degrees at noon in Moose Jaw, Sask on the motorcycle and that is about 20 degrees too cold for my motorcycling comfort. No heat wave up here. Rain yesterday at the Farm Progress Show in Regina but nice at it the day before.

I am taking out all I can. Only got one this morning at 2 lbs 1 oz and 18-1/2". We had it for lunch. Sometimes they don't bite.

Got two more CC on hot dog pieces yesterday evening. Have now taken out over 23 pounds since the low DO event. I wonder how much it will take to make the pond safe until fall?

What is the bio load of your pond now? That is the real question. The experts will tell you if you are overloaded. I believe they would ask for size and average depth. Inflow and out flow will also be contributing factors. Water quality and wind over the pond are a few other things to consider.

I don't know the true bio load. I have BG and RES in addition to the CC. A few of the BG (10-15) are 8-9 inches, most are under 7 inches, maybe 100 or so 6-7 inches, plus recruitment. I don't know how many CC are still surviving, but only found three in distress along the bank since the event. I suppose the CC bio load could be as much as 160 pounds, or as little as 90. It's quarter acre, current depth 10.5 feet. I pump water in from the creek when there is flow to keep the level up. No creek flow now, but pond level still good. I also removed about 250 pounds of FA since the low DO event.

Going fishing for CC again this evening.

Sounds like you are headed in the right direction. I would take more CC out, and try to get a handle on the BG and RES numbers. If you have a seine or cast net, I would sample the pond. It would be a good way to "take a look" at your numbers.

Also, you might want to add one or two female LMB to keep recruitment down some. And they would be fun to catch as well!

I agree with Brian. Food for thought.....I've read that 1000 lbs per acre for a catfish farm with heavy aeration is a lofty goal. Your pond is a 1/4 and not aerated. I would try to remove at least a total of 50 to 75 lbs of CC and BG combined.

John, you know I ain't no pro but I'm here in the cheap seats routing for ya!

I caught four more CC this evening, totalling 11 lbs 7 oz. I have now removed over 34-1/2 pounds of CC since the event.

A few weeks ago I put in five LMB from 5 to 8 inches, and there was already one in there about 14" (don't know how it arrived for sure).

FHM population is already way down; there was a lot of minnow biomass in early May, and large numbers of young BG from last fall.

We don't have freezer space for many CC, so we are eating a lot of them as we catch them.

BG really aren't big enough to eat. There is too much structure and FA to use any kind of capture net.

The CC have huge amounts of yellowish fat in their body cavities around the intestines and liver. It has the consistency of lard.

I have cut way back on feeding for the past nine days.

As a very general rule of thumb if a pond has reproducing fish populations and the fish have been in the pond for 18-24 mths under normal conditions then the pond has reached its carrying capacity absent some enhancement (water quality improvement , feeding or fertility addition). From then on its a matter of managing the fish by size , condition and manipulation. One critical concept is total fish mortality (how many have died) with harvest being an important part of that equation.

Update 6-27: We caught and cleaned four CC weighing a total of 12 lb 7 oz. They averaged about 110% RW. That's a total of 47 pounds of CC removed since last Tuesday. They are not super easy to catch.

Just out of curiosity, What are you using for bait?

We caught the first eight on chartreuse or pink crappie jigs, but they quit hitting jigs completely. The last 10 we have caught on pieces of cheap pork/chicken hot dog, fished under a small float about 18 inches deep over about six feet of water.

As of this evening, June 29, 52 lbs 5 oz removed since low D.O. event. Getting there slowly.

John, you know the fish in the pond better than we do. Try to estimate the total weight of the fish in the pond of all sizes in your head. In non-aerated pond I wouldn't try to push the biomass any larger than 400-500 pounds per surface acre, so in your quarter acre pond, without any aeration, a total fish weight of 125 pounds could be pushing it.

Adding the creek water with the trash pump is helping. The lowest point of the day for O2 levels is right before sunrise.....

Scott, I have removed over 76 pounds of CC since the event. They are good eating, and fat! Getting harder to catch.

The huge numbers of tadpoles have almost all become frogs, so that lessens the biomass some too.

I already had one or two LM bass, and a couple months ago, I put in five more at 5 to 8 inches to get rid of huge numbers of FHM and small BG. I think now I have a net biomass loss in FHM and small BG compared to the LM bass biomass. The CC have not been good FHM and BG predators. They are lazy and prefer pellets.

The creek has no flow now, so no pumping.

Today so far we have removed a few hundred pounds of FA by wading using leaf rakes. I think that helps too, as the FA under the water is black looking. Since the low DO event probably 500 pounds of FA has been removed. The garden is mulched with it.

Edit 7/21: Right at 80 pounds of CC removed since the event.