Every year when the weather gets hottest my HBG slow way down on eating. We've had mid 90's the last few days and my fish hardly eat a thing. They do this every year. No other problems that I can see. I can occasionally catch one and they are just as healthy as scrappy as ever but just don't eat much. Water temp is 79 degrees on surface and 77 degrees 3 feet down. Is this too Warm for them to eat? Any expert bluegill guys have theory on this?

Bz,

A most interesting and timely post from my perspective. I'm having a problem in my TGG pond with virtually no fish activity...suspecting poaching and/or seining because of a lack of fish activity...and am most interested in your experience on this matter.

I hope Bill Duggan or any others with experience on HBG will weigh in on your question. I either have the same behavior in the TGG pond or the fish have been removed...until your post, I was thinking the latter, now hoping its the former.

bz, Meadowlark, the timing is very interesting. This time of year the LMB at our pond get a lot tougher to catch primarily to due the abundance of YOY fry and aquatic insects in the water that are now sizeable enough for the LMB to be interested in. I wonder if your HBG and TGG are chasing YOY fry and insects instead of pellets? I have always considered this time of year to have the most abundant natural forage base for the fish than at any other time of the year. It is about mid July every year that the LMB fishing starts getting tough in NE. IMO the natural forage base is nearing it's peak of abundance for the year.

Shorty,

Yes, I know exactly what you are saying. In my case, however, it's more than that.

One of the key indicators in the little TGG pond is the Gambusia. Very few Gambusia along the grassy shoreline equates to active, feeding TGG fish. Lots of Gambusia everywhere, in my mind, equates to either no TGG fish or no feeding fish.

In the last three weeks, the TGG pond has become covered with Gambusia. There are thousands of them evident everywhere. I have Gams in other ponds also, but everything is normal there...i.e. few Gams along the shoreline grasses. I hope Bz is right about an activity slowdown or "work stoppage".

As Theo can testify, I have been concerned for the last few weeks that the TGG were AWOL. Bz has shed a ray of hope that perhaps they are only MIA at this point.

Ditto Shorty's thoughts assuming no water quality problems. Others including CB1 and I have reported the same with their BG in the past. I will note the obvious that the reason there is so much growth in summer is because that is the thermal sweet spot for pond life (growth and feeding)including fish. At least until it gets to hot (Aug. in the south). BG thermal range top 96.8 , GSF 89.6 . This is not the lethal top temp. nor does it mean temps. don't effect them at a lower point (as in reduced activity and feeding). Also there can be local genetic adaptation to lower or higher temps.

ML and bz I will do some checking on your question. ML there may be so many Gams. that the GG can't control them with all the other food available. They may also have started feeding at night with no LMB present. I assume HSB are not big night feeders but don't know that.

ewest, am i understanding you correctly when you said above the BG thermal range is ~97 degrees? they can survive in 97 degree water? and their range is ~7 degrees higher than for GSF? i had no idea.

i might get a chance to fish the downstream ranch pond Sat. morning.....temps have been close to and will reach the 100's this week.....it will be interesting to see the change (if any) in the catchability of LMB and GSF down there.

Our CNBG are feeding vigorously on an early morning AQMX 600 schedule, having stopped evening feed.
Near surface late afternoon water temp 87 degrees last time checked.

N.E. Texas

Here is a start.

Growth Rates and Temperature Selection of Bluegill, Lepomis macrochirus
THOMAS L. BEITINGER and JOHN J. MAGNUSON

Laboratory of Limnology, University of Wisconsin, Madison, Wisconsin 53706

Abstract.—Growth rates of individual juvenile bluegills fed 0.75, 2.0, 4.0, and 6.0% dry body weight day-1 and ad libitum at constant temperatures were smaller above (34 C) than within (30 or 31 C) or below (25 and 28 C) this species' preferred temperature range. For each feeding regime growth rate did not differ significantly at temperatures below 34 C.

ewest and others,
HSB striped bass parents are voracious night feeders on the full moon, currently the present full moon phase, as well at first morning light and late evening.

A summertime favorite striped bass pattern is to fish the cooler night hours on the full moon, wait silently for noisy topwater feding activity and follow the fish.
Better hang on to your fishing rod....

George thanks for that info. Do you (others feel free to answer also) think the size HSB in ML's GG pond are sufficient enough at night feeding to effect GG night feeding by predation ? In your experience do you think HSB are as strong of night predators during the summer as LMB ?

It is my practice to avoid fishing during the full moon phase.

IMO all species feed at nighttime if clear skies and full moon, and will normally suspend in their “comfort zone” during bright sunny daylight hours.

By the same token, I love to fish drizzly overcast days but haven’t seen many of these lately.

I don’t know the size of ML’s HSB – mine of the same year class are running 12-14 inches to about 1 1/2 pounds.

Interesting discussion. In the past I have attributed this yearly slow down to the abundance of other food but I have always wondered if that's a good conclusion. I bring it up now because so far this year even if they aren't feeding well in the morning they generally will do better that evening or vica versa and I can always get them to eat things like grass hoppers when I throw them into the water. The last several days they will hardly eat anything. I throw bugs in and they just float there. The few fish that do eat are the smaller ones during the day and the larger ones during low light hours. My experience is that my fish easily consume about a pound per feeding very quickly earlier in the year. But this time of year they hardly eat a thing. It's a waste to even throw any pellets. The reason I question my hypothesis is that I noticed that if I can entice a fish to bite a hook they are healthy but not fat. So I don't think it's because they are stuffed with natural food. I also noticed from my records that my fish don't grow much during the months of July and August. Their major growth is May and June with some minor growth occuring in September.

ewest did mention water quality issues as a possibility, strong algea blooms and wild fluctuations in DO levels overnight could reduce feeding, especially during the early moring hours until DO levels start to rise. I can tell that during one of the copper sulfate related DO sags we had once that fish wouldn't eat at all. Their more immediate need was finding oxygen.

How might aeration come into play with this discussion?
Would aeration affect feeding activity, whether warm water or time periods?

We are currently running three air stations in a 2-acre pond (N.E. Texas) nighttime and morning hours, and not experiencing fish feeding problems.

George, I think aeration or the lack of any aeration could easily play a large role in how actively the fish are feeding at this time of year. The higher the DO levels are the more I would expect them to be actively feeding, as DO levels drop I would expect just the opposite.

Could be aeration. Although I have never found fish gasping on the surface or anything that severe. I also find the fish to be quite scrappy when I can hook one. So I've always figure it probably wasn't oxygen. The last few days were hot but I had a nice wind running the length of the pond enough to make waves. I have had no algae blooms. I also notice this time of year that the fish feeding most are in the most quiet and stagnant part of my pond far from the aerator. Right where I'd figure there to be less oxygen. I might try running my aerator more just to see if it makes a difference. This could all be answered if I had a DO meter but can't afford one.

bz I don't think its DO - not with those temps and aeration and your wind action. So far I can't find any info that would indicate its temp related with 80 degree water. That is prime temp. for both GSF and BG to eat , grow and be active. Have info on activity being good on BG up to 95 degrees even with relatively low DO's. Still looking.

This has always been the case in my pond and I've often wondered how you southern pond owners ever get fish to eat when your water is probably over 80 degrees for 6 months straight. My water might get to 83 or 84 degrees max. and it seems to slow the fish down. Maybe it's just like me traveling to Mississippi where I can't function too well cause I'm used to northern climates. Or perhaps it's got something to do with the moon, or comsic rays?

bz no doubt that there is local genetic adaptation and conditioning and it is a factor. The info I have been using in making these comments is from all over including other countries. The one I posted yesterday was from Wisc. One thing I was checking was to see if HBG were much different from either parent species wrt temps.. Nothing indicating that yet. Interesting question and I will keep looking.

bz after looking and finding lots of info but none directly on point I had a thought about your question.

A few points first. I doubt it is a DO problem or a max temp problem and those have been covered above. When I went to the pond today the warmer of the 2 ponds was having the same situation as yours -- BG feeding had slowed way down. The cooler pond did not have this condition. These ponds are 400 yards apart but different watersheds. The cooler pond is smaller and has much more spring effect. The warm pond was 89 at the surface up 10 degrees in in a week while the cooler pond was 82 up only 3 degrees. This week we have had our first extended 92 + temps all week and no rain to cool the surface.

Then I remembered from the studies that BG had different best temp ranges for different functions. Top swimming speed at one range , top growth at one and most active at another . All were close but different. In the studies one thing measured was how well they adapted to changes in temps over time . If the temps rose slowly they did well but if fast not so well. They would stop a lot of activity until they adjusted. Same for temp reductions.

We all know that is the case wrt cold fronts in fall/spring/winter. If you get a big temp change activity stops until the fish adjust. So why not with a sudden increase also.

You had described this wrt your pond and that is what must have happened with one of mine. I found no info that indicated a max temp problem with BG or HBG at any temp below 95 degrees and plenty from all over - Canada to Mexico and over seas that provided that 72 to 85 is an ideal range for them.

If others have encountered this or have thoughts or comments please join in.

Intersting conversation. I looked over several publications to come up with feed guide for clients. May bnot be applicable in Minn. I agree maybe it is relatvie change in temp b.c if 77 here they would be doign well on feed. ANyway here is my free info do with it as you will. Sorry for copy and past format.


Fish Feeding Recommendations
The Aquapro line of feeders makes fish feeding an easy to accomplish task. It is superior to hand feeding due to multiple feedings per day and the consistent time in which it is cast. Different models and types of feed will disperse at different rates. Due to this it is best to set feeders by feeding activity rather than a set feeding duration.

As a general rule of thumb, only cast enough feed so the fish will eat most of the food in 5 to 10 minutes. Over feeding may cause dissolved oxygen depletion and possibly cause a fish kill. The total amount of food consumed will vary due to surface water temperature, fish species and water quality. The size of pellets and protein levels vary with species but catfish grow fine with 32% while rainbow trout require 42% or greater.

The amount of food and feeding times change with the seasons. Maximizing growth and feeding efficiency for warm-water species is best in spring and fall for southern climates. Bluegill feed best when water temperatures are 65-80F. Hybrid Striped Bass feed best when water temperatures are 75-85F, but feed poorly when water temperatures are below 65F. Catfish generally feed best when water temperatures are 75-85F. Rainbow trout are cold-water species that feed well in cool months of the year. They feed when temperatures are 50-65oF and die at temperatures exceeding 70oF.

The feeders are great for feeding all of these listed species and many more. Catfish have only marginal benefits from multiple daily feedings. Many of the feeders are sold to clients wanting increased bluegill growth and subsequent increase in bass forage through their growth and increased reproduction. Below is a feeding guide for bluegill based on the water surface temperature. It is designed to maximize growth.

Bluegill will not travel far to consume food. In order to maximize bluegill growth and production, it is necessary to setup multiple feeders in ponds greater than 1/2 acre. All ponds are shaped different but typically a minimum of 1 feeder per acre may be necessary to feed all bluegill all smaller ponds. For ponds greater than 10 acres 1 feeder/2acres are sufficient.

Water Temperature Below 55F
Feed only one time per day, during the warmest part of the day. Set the automatic feeder for one second. If fish are not feeding, discontinue feeding until water temperature increases above 55-60F.
Water Temperature between 65F and 80F
Feed 4 times per day. Temperatures between 65-80F are ideal for maximize fish growth and production. Bluegill have small stomachs and cannot consume large quantities of food per feeding. However, they will feed aggressively at these water temperatures. Separating the feedings by a few hours allows digestion of the food prior to next feeding.
Water Temperature between 80F and 90F
Feed 2 times per day during the cooler parts of the day, typically at sunrise and sunset. The amount of food may need to be decreased as temperatures continue to rise. Discontinue feeding when water temperature increases above 90oF and start back up when it drops to 85F or less.

Thanks Greg that seems to follow what I have been finding. I think that will help to lessen the trial and error and let folks know what to expect.

Thanks from me too Greg. The general trend seems to follow what I've been seeing except that my fish slow way down when temps get over about 75 deg. My fish feed and grow the most in May and early June when the water temps don't get over 70 and then slow way down in the high 70's. My temps have never gotten much over 80 so I don't know what they'd do if I moved them to Texas.

Why heck they would join a rodeo, eat beef jerky, and increase their protein intake two fold.

I have always found it safe to play the 15 minute rule. Feed whatever they will eat within a 15 minute period, and then stop feeding. Overfeeding can lead to various problems (as discussed before) for different fish. Cats will possibly gorge themselves until they pop, while other fish tend to move into cooler waters if available leaving the feed to mold or turn the pond otherwise "unhealthy". I have noticed that the GG tend to snack on the gambusia throughout the summer regardless of the heat. Not sure about the standard BG though.