Pond Boss Forums FISH & FISHING Sunfish-Including Largemouth and Smallmouth Bass Algae and Dying Bluegill ... a connection ?

I have found 3 dead bluegill floating in my pond in the last few days (seldom find dead fish). They are all jumbo size bluegill and may be ones I transferred from a local lake 7 weeks ago to hopefully help add to the forage base............. although not sure because I already did have some fairly good size bluegill in the pond. The Filamentous Algae started about two weeks ago with onset of warm weather and is pretty bad this year - I am now just getting around to spraying it with Mezzine as I have done in the past.

I am puzzled (and anxious) why this is occurring and why only the largest bluegill in the pond are being affected ? Nutrient wise - we had a long spring this year and the Canada Geese that visit during the winter and spring were more numerous and stayed longer than normal, I have 5 grass carp approx. 15 lbs each, and last week I fertilized the lawn surrounding the pond with some 23-4-10 fertilizer.

Because I irrigate the lawn out of the pond, it receives daily approx 6000 gallons of fresh water from a nearby river that is known for being super clean (snow melt - no industrial contaminators).


Pond specs:

20 years old
1/2 acre
11'-12' deepest part
Water temp - measured 3 PM .......... 82.1 F surface and 78.8 F down 3'
Incoming water temp 70-72 F (6000 gallons daily)

So is there a correlation with the Filamentous Algae growth and dying bluegill or ................??

Thoughts on this appreciated.

https://photos.app.goo.gl/Q7PfSoQDr3CwoX4k7

It could be just old age.

The forum is having problems showing pictures that aren't hosted on another website, like Imgur.

Thanks for the response. Maybe I should have taken them in for their annual Medicare checkup before stocking.

3 more dead bluegill since last post - all large fish. Heat wave continues here and using a Minn Kota digital thermometer recorded surface temps of 85.5 degree yesterday and 87.3 degrees today. I didn't realize fish could take that kind of high temps - unless they are all down in the bottom of the deep end.

Now I am wondering if high water temps are playing a part in what is happening - but again, why only the largest bluegill ?

The very young, the weak and the old are the first to show up. This is your warning signs.. they need aeration, there is no DO in deepest part of pond, in fact it's toxic. Do you have a way to aerate?

Currently splashing 6000 gallons of water a morning into the pond via a one inch pipe supplying river water at 77 degrees. I can increase that to 12,000 gallons if needed. That would be the only aeration that I have available short of using a small pump I have to pump the water out of the pond and send it back in again.

Aeration suggestions ?

Moving air is a LOT cheaper electric wise than moving water. The Vertex PondLyfe systems have 1/3 hp motors. Basically a plug and play, nothing to piece together; we sell complete systems, self weighted hose and all.

Now since it's so hot out if you put an aeration system in you need to do the week long start up procedure.

If you still wanted to use the river water, you could run it through a packed column to add a lot more O2 to that water, and it will cool it down by a degree or two via evaporation by doing that too.

Pond Star, do you have AC grid electricity available at your pond?

If you post "yes or no", you will get much more relevant answers on your aeration advice.

We are lucky that the forum has many aeration experts, and several solar experts if you have to create your own power at the site.

Thanks for the suggestion - yes, I have AC available at the pond.

I have a rainbird type sprinkler that sits on a stand - would that help to spray water into pond with that ? otherwsie water enters pond thru a 1" pipe three feet above the pond surface.

Will be shutting off other use of river water today and will be able to spill 12,000 gallons river water into the 1/2 acre pond before my time allotment for water expires. River water running at 75 degrees this morning under slightly hazy skies. Pond still in low 80's.

Normal feeding of bass and bluegill this AM attracted only one LMB - praying the others aren't dead as they range up to 4 lbs.

High temperatures expected again today

No observed morts this AM

Good deal having AC electricity. That makes installing aeration much simpler and much less costly.

Dissolved oxygen in water is also a function of temperature. Cool water can hold significantly MORE oxygen. I think your plan of maximizing the input of cool, naturally aerated river water should be a great benefit to your fish.

Hopefully, that will get your fish through this crisis period.

To avoid a future crisis, you might want to start a new thread in the Aeration sub-forum and post your pond circumstances. You should be able to get some really good advice from the Pond Boss experts on that topic.

Thanks very much for the input

Any thoughts on whether the sprinkler idea would be helpful ?

Is the sprinkler water from your river allocation?

I don't know if the river water is fully oxygen saturated. If not, then the water taking a trip through the air as small droplets from your sprinkler can only help add more oxygen to your pond water.

The sprinkler water would be in addition to the 12,000 gallons of river water. It comes from a water association that supplies the domestic drinking water for the house - it is from the same river, but of course gets some mild chlorination and whatever other "cleansing" procedures it goes through. It is expensive at $5.00 per 1000 gallons, but since I may be at risk of losing my fish I am resigned to some extra cost if it helps.

That is a little pricey, but they are your fish!

Your oxygen minimum is usually the last two hours before sunrise. Can you put the sprinkler on a timer for those two hours? That should give the fish some relief. (Unless you want to go 24/7 until the crisis is over.)

Cannot put that water source on a timer currently - so best can do is to turn it on can manually first thing in the morning. River water temp dropped by two degrees today as we got got a haze that set in - and air temp only got to 90 degrees compared to the 100-105 it has been the past few days.

Put in 12,000 gallons of river water and ran the sprinkler for 4.5 hours - so hopefully that is helping along with the air temp drop. No morts found today.

This water has chlorine in it?????

Yes- what's a little chlorine amongst friends ? I figured with almost a million gallons of water in the pond some water with a little chlorine in it was worth the risk for the aeration I was looking for. This is not the 12,000 gallons from the river - it is domestic supply for the house from same river but is treated at the plant before getting to the house. So today the pond got 12,000 gallons of river water and probably about 1000 gallons of the chlorinated via sprinkler.

Maybe not such a good idea ??

Probably not an issue at that dilution.. I misunderstood the water source.

I’ve often heard that sprinklers are more aesthetic than helpful for aeration.

My opinion is the problem is directly related to the temperature of your water. While bluegill are more tolerant of heat than Largemouth bass, the larger, order bluegills don't like water temps in the upper 80's. I've gotten several reports here in Texas of bluegills dying as a result of the heat, especially in aerated ponds where the system runs 24/7. There is no thermal refuge in ponds aerated 24/7 in the hottest parts of the year, in the hot climates.

The sprinkler is irrelevant. I'd bet, if you check dissolved oxygen, most of your water is above the lower lethal for any of the species. That's why I think temperature is the common factor.

I found two large male bluegill floating a week ago. I would like to assume it is from old age possibly accelerated by stressors or exhaustion from spawning and the increased water temps. I have not found any smaller bluegill or HSB thus far. I would assume if it was simply temperature related there would be several bluegill dying in a similar fashion. Just my thoughts.

Again, as stated above, the first to go are the old, the weak and the very young. I think Lusk has made a good assumption.
You may not have stressed/weak fish of a smaller size, you may not have YOY that you would even see if they perished but what Bob says aligns with what I see this time of year.

Thanks Bob -

So what do you suggest on aeration time if 24/7 in the heat is not a good idea ?

Presuming I have a high nutrient load in the pond , will aeration of some amount help with reducing the floating algae mats ?

How does one measure dissolved oxygen- and what are the danger numbers ?

Pond star, Bob will chime in when he has time, but I will try to lead you in an acceptable manner.
First, aeration is best at night in the hottest time of year. We don't want to roll that upper layer of 3-4-5-6" water that is 4-8 degs higher than what's underneath .. #1, the higher the water temp, the less dissolved oxygen it will hold.
Some of the timing on this depends on the output capacity of your aeration system and the efficiency of the diffuser/s.
Some species of fish have different tolerances of D.O., but a solid number to stay above is 4ppm. Higher is better, and to get higher we need to drop the water temp so it can hold more..aerating at night without the day cycle is how we can best do this.
Photosynthesis creates DO as the O2 producing organisms "bloom" during daylight periods. The problem is we heat the water aerating in the daytime and warm water holds even less, so really, we are hurting the oxygen levels by simply rolling warmer water into the mix, or more accurately, moving the cooler water to the surface and effectively warming it.
I'll step out on a limb here and say I believe Bob will say 9pm to 9am on aeration. He will correct me if that's not what he'll recommend.
Nutrient loads and aeration: Aeration will help to some extent by providing DO to deeper levels that allow beneficial bacteria to thrive in what would be normally low or absent DO aera to more likely consume detritus/organic matter and reduce unused nutrients-REDUCE not remove.
As for the algal mats, aeration basically pushes it to the sides of the pond but it really has no other affect on algae. Best thing to do with algae (nutrients locked up) is physically remove it when you can reach it..
I have to back up here... floating algae mats are nutrients that are tied up, it's not a free nutrient, but as it dies/is sprayed, it decomposes and the nutrients are released back into the water in their basic forms which can be used by aquatic plants or form as algae mats again.
As for measuring dissolved oxygen, there are some very expensive digital type meters with probes that can be very accurate but can also be very temperamental. I use a chemical test kit for DO measurements but can only measure to a depth that is the length of your arm. Plenty sufficient in most cases. The La Motte kits are very useful if you follow the guidelines closely.
I hope I've helped answer some of your questions in a manner that makes sense.

Snipe-

Thank you for the detailed explanation - things are becoming clearer the more you and folks like you post about this problem I am facing. Have always had som algae matting in the summer - but nothing like what I am seeing now. Today 1/3 of the 1/2 acre pond is covered with mats ............... can this in itself become a danger if left unattended and they cover more and more of the pond and eventually have the possibility of no open water ?

Can aeration be of a fountain type (my wife's choice of course) or should it be a diffuser system set on the bottom of the pond ?

Where can the kit(s) you mentioned be purchased ?

Again - thank you and other members so much for helping me understand what I am dealing with here and what to do about it.