Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations 4 year old Catfish all dead

Hello folks. My name is Don and I'm new here and thank you in advance for any suggestions that you might have. I live in NE Ohio and my pond is approximately 1 acre and 9 ft. deep.

About 4 or 5 years ago, I had a winter kill that wiped out all the fish in my pond. I am pretty sure it was just too much ice covered with too much snow for too long. I had some nice sized bass and some catfish and the usual assortment of sunfish, perch, etc.

After the kill, I installed an aerator to ensure that it didn't happen again and I run it enough in the winter to keep the ice open. I then restocked the pond with fingerlings. Hybrid Blue Gill, Yellow Perch and Channel Cat. Also some minnows for food source. I only went with a few Channel cat, I don't remember for sure but probably only about 20. All has gone well. I feed very occasionally just because I enjoy watching the fish come eat. Usually only maybe half a coffee can full of food about twice a month.

The blue gill and catfish have grown very well. Not sure about the Yellow Perch, I never see any but haven't fished either. Over the 4 year period, the catfish had gotten pretty large, probably between 5 and 8 lbs. Loved watching them eat and they would almost eat out of your hand. Until today.

I went out to the pond today to find what is probably every single catfish dead and floating. Most around the edge of the pond now but a couple out in the middle. I can see nothing that might have caused them to die. There are also maybe a half dozen other fish dead but not many. I threw a bit of food out and the blue gill and sunfish still eat aggressively.

I hate that I lost the catfish. Is there some disease that would have killed them? I've had probably 25 or so Canadian Geese camped out here for a couple of months now but they usually come every year. There are also a couple of large Blue Herons that visit a couple times a day. Could the geese or Herons cause this?

I also have a deep well that I use only for irrigation. I have a float on the pond that is hooked to the well so that level stays constant. I've been doing this for over 4 years also and had the well water tested before doing so and it is good water, actually even suitable for drinking. Just mentioning it in an attempt to not leave any details out.

So, any ideas?

Welcome to the Forum, dknelson ("d" isn't by any chance stand for "David", does it?)

Sorry to hear you have lost your cats. I had one question to ask but I saw you already stated that the BG are active, just a few dead.

We'll be coming up with some ideas & questions.

I apologize for Theo's reading comprehension, Don.


I'm sorry for your loss. How would you describe your water quality? What color is it? Do you smell anything odd (other than dead fish)? What is the visibility?

I would say that the water quality LOOKS very good. It is not real muddy or cloudy. There is a stand of catails on one side that I'm going to have to deal with soon but they haven't taken over. Some usual pond grasses but nothing bad. I could take and post a picture of the pond but it is really pretty nice.

We all like pictures!

OK...these aren't great pictures but maybe you can get an idea about the condition of the pond.

Hi Dk, I'll leave the answers to the experts. I just wanted to welcome you to Pond Boss, we're glad you found us.

Great photos!

Thanks for the welcome. I do have one thing to add that may or may not matter. As I stated in my first post, I have a well on the property. The water in the well has been tested and is good. We don't use it or drinking water, only irrigation and etc. but we could drink it.

I have a one inch line from the well to a float valve in the pond to maintain the water level where I want it. I noticed yesterday evening that the valve had gone bad so the pond has been getting a constant infusion of well water at a rate of probably 20 gallons per minute. I have no idea how long this has been going on but I would say at least a couple of months.

Could this have anything to do with the catfish dying? Is it possible that all that fresh water has flushed out some natural elements that the fish needed? I have a stand pipe type overflow with a grid on top so the level has stayed full but constantly flushing. The dead fish look very healthy...well...except for being DEAD.

I'm sure the expert will chime in on this DK. One issue with well water is that is typically lacks oxygen. At 20 gallons per minute you are introducing 28,800 gallons of well water per 24 hour period. A one acre pond that is 9 feet deep contains just over 2,932,000 gallons. Therefore in every 24 hour period you are replacing just under 1% of your total pond water. So if this was continuing to happen over a 60 day period then you have replaced approximately 60% of your pond water during that period. I have no idea what effect that has but I'm sure one of the knowledgeable experts here do. (I'm just a bean-counter that can't resist an opportunity to perform basic math calculations. Consider yourself lucky that I haven't generated line graph or pie chart or something).

How does the well water enter the pond? Does it just pour out of a pipe into the pond, or is there a water fall? What I'm trying to get determine (and I would imagine the experts will ask you) is that is the well water receiving any oxygenation before or at the time of entry into the pond.

We'll let the experts get back to you on answers.

20 gpm is a lot of water, but it's not a huge amount of water wrt a 1 acre pond. Most well water is OK for fish to live in, albeit it usually has no oxygen when it comes out of the ground. I don't think 20 gpm of low oxygen water going in to 1 acre would be the problem that killed the catfish.

New angle. Can you describe your aeration setup and schedule? 24/7 or what?

The well water enters the pond under the surface. There is a float valve hooked to a 1" water line with a nipple that in under the surface. So...it has no chance to pick up oxygen as it enters the pond.

I basically only use the aeration in the winter to keep some holes in the ice. It is an electric 1 HP motor hooked to a aeration pump. I have two stone type aeration blocks in the bottom of the pond. I will occasionally run it in the summer if the water starts getting nasty looking but have not run it this summer except for maybe a few hours once or twice.

So you could easily have been stratified at the time the CC went. Did you happen to run the aerator just before the cats died? Any major cold rain events preceding the deaths?

No, I have not run the aerator in probably at least 6 weeks or longer. We had a wet spring but no rain lately, in fact, it's really getting dry around here.

One other thing that I have thought of though. I built the little pier about 4 years ago. I built it so that it is out of the water about 1" or so when the level is normal. With the water valve staying open, the water is above the bottom of the 2 x 6 skirting by about an inch maybe. This is treated lumber. Could the fact that the treated lumber was partially submerged have caused some leaching out of the chemicals in the lumber that would have killed the catfish? If so, why has it not, yet anyway, killed the sunfish, minnows and blue gill?

I would lean towards low DO,seems med to large catfish can be the first to go. I would "slowly" start up the aeration system and also get some splashing at the surface at the same time. A 1 hp pump can produce a lot (possibly too much ) air depending on what type stones you have, you can also bypass some of the air to the stones to slow things down. The surface aeration is of great value if DO is the cause, DO NOT turn the bottom aerators on 24/7 as you will lower your DO in the upper water before you raise it. If you know the specifics of you system (pump type, model Gast 1423 is a 1 hp rotary vane for example,4 or 6 stone plate etc) I probably have the lifting specs on it and can advise you You are starting to get some cool nights in your area as we were 53F in NW Ohio this AM , this is going to sink or push down the higher surface DO that many other fish may be depending on.I dont think treated lumber was the problem as you would have more than just the cats gone. I have had treated in mine since I rebuilt the pond in 2002 with no problems.Consider acting now as this could be the just start of things

FWIW I have lots of PT lumber in my watershed and over my ponds - fence posts, fence boards, docks, etc. "Doing all right so far!" (What the optimist said for 99 floors when he fell off the 100 story building.)

Well, I've turned on the aerator for now. I think I'll let it run for about 4 hours and then shut it off again. I guess only time will tell now if my bluegills and etc. start dying.

A cautious startup aeration schedule would be 1/2 to 1 hour the first day, working up and hour or so each day.

Thanks...I should have waited for an answer. I ran it for about 2 hours before seeing this post. It's off now. We'll see.

Perhaps you should have asked; certainly we should have advised.

You might want to read through the Archive "Aeration Simplified" thread and it's links for further info.