For some reason the last 2 years my bluegill population have gotten a bacteria infection around end of May. I just started giving them some homemade medicated feed today to hopefully get ahead of it but last year I lost quite a few fish from this same problem (see attached picture).

Anybody have any suggestions for how to figure out what's going on to prevent the fish from getting infected every year? I added an aerator last summer hoping to improve oxygen levels and overall water quality but the infections came back this year right on schedule.

I imagine if I could help the fish's slime levels somehow that would prevent this but not sure how to go about it. The bluegills are probably overpopulated in there and that's not helping anything but an abundance of food definitely helps the the bass so that's the reason I'm not harvesting them.

Can't tell much from that pic - do you have more pics or descriptive write-up of what you are seeing. BG spring infections are not abnormal but quite frequent.

Have you tested water quality in the pond? I would think your O2 is probably okay, but there is more to it than that. Perhaps something is at its most marginal for BG this time of year, making them more susceptible to infection.

A water quality test would be great. We don't have any "pond shops" nearby though. Do you have any recommendations for where a sample could be sent or what it should be tested for? I think you're right that something in the water happens this time of year and pushes the bluegills out of their normal range. Be nice to get it sampled now while the problem is occurring.

Ewest - I talked to a biologist last year when it happened and they said it was a bacterial infection. The bluegills develop red spots on their bodies, start to loose color on their fins and their mouths and tails start rotting away.

Update: Found a mail in water sample place about 1.5 hours away so got a kit coming from them. Will be interesting to see how it tests.

Check red sore disease.
http://fisheries.tamu.edu/files/2013/09/Red-Sore-Disease-in-Game-Fish.pdf

Thanks ewest, that's exactly what it is! From the article "Heteropolaria thrives if there are high levels of organic matter in the water to provide nutrients. Stress, caused by poor water quality, crowding, water temperature variations, reduction in body condition, or spawning can increase the susceptibility of fish to red sore disease."

I think it's a combination of high nutrient levels from feeding, being crowded and spawning stress. It creates a perfect storm for this issue it seems like. Water quality might be a piece of that puzzle too, hopefully know more in the next few days. I'm hoping that improving the water quality helps as that is the only variable that would help my goal of bigger bass. Less fish or feeding them less would go against that goal.

See red above added to your text - those are the factors for many problems. The last red notation- only variable that help - is one but not the only one -- harvest/removal of small underperforming fish would be a big help.

Wouldn't the smaller to mid size bluegills be the ones most targeted by bass? I wouldn't think too many of the big bluegills are getting eaten.

I could also try and fish out some of the bluegills that aren't feed trained (regardless of size). Perhaps that would help reduce stress and keep the feed trained fish healthier.

The bass will target BG that are 1/4 to 1/3 their body length.

That is helpful. My biggest bass are around 22" but there's not too many of those (lot of 15-18"). I think I'll start fishing out the bluegills in the 6-7" range. That will keep the best breeders (8"+) and help take some stress off the ones that I want to stick around for bass food. Does that approach seem reasonable or should I be harvesting a range of bluegill sizes?

On a side note I never realized how many little bluegills were actually in there until this fish kill started.

Sounds like a plan. You won't ever catch out all the 6"-7" BG, so whats left will be the upcoming crop. You DO need to take out 20# of bass per surface acre to keep the bass numbers in check too.