this bluegill was just floating in this position, with its mouth out of the water, occasionally propelling itself with its tail fin.

any idea what is wrong with it?

PS: this bluegill is in the same lake that had the big shad kill last week which i read in the newspaper was due to low oxygen levels because of an algae bloom.

You answered the question. The lake has a Low oxygen level and that fish can't breath.

ok but why is it's mouth all decroded looking?

That looks like Algae that is stuck to it's mouth.

I've seen this behavior in aquariums, even with bluegills. Due to low O2 the fish get very inactive and hang with mouths at the surface. Air holds much more 02 than water in general, but fish can't really access it. (Some species can suck air into their air bladders and breath this way, when 02 gets low. Species that evloved in low 02 waters can do this: bowfin, mudminnows. But bluegills can't as far as I know.)

The bluegill you saw is probably gaining the precious little oxygen that diffuses into the water at the surface, and trying to stay inactive so as not to burn much. It's a last ditch effort to save itself.

Sounds like that lake may have a fertility (sewage, fertilizers, siltation) problem. Is there a lake association that can address the problem?

You answered the question. The lake has a Low oxygen level and that fish can't breath.

I aggree 100%.

It's obvious that this fish is gasping for air.

Question: Would a good rain fall help get the needed O2 in that area?

I would imagine a good rainfall would boost oxygen levels... if not only temporarily

100% to low of oxygen in the water

A good strong wind for a few days probably wouldn't hurt either.

You answered the question. The lake has a Low oxygen level and that fish can't breath.

X2!!!!!!!!!!!!

Question: Would a good rain fall help get the needed O2 in that area?

The greatest depleter of DO is rainwater as it in itself is void of beneficial DO gain. Heavy rainfall and its associated runoff is the most prevalent cause of fish kills in lakes and waters already having low disolved oxygen.

You answered the question. The lake has a Low oxygen level and that fish can't breath.

I aggree 100%.

It's obvious that this fish is gasping for air.

time was my saying something stupid like this would have brought a chorus of derisive howls.  All in the spirit of camaraderie of course.  but still... :

Question: Would a good rain fall help get the needed O2 in that area?

The greatest depleter of DO is rainwater as it in itself is void of DO. Heavy rainfall and its associated runoff is the most prevalent cause of fish kills in lakes and waters already having low disolved oxygen.

Wow great info. I certainly was not aware of that. Good post.

That's one disturbing photo....could the DNR in this state do something??

Alan

That's one disturbing photo....could the DNR in this state do something??

Alan

i hope so! :-/

Many species gulp air to supplement low oxygen levels but I didn't know that bluegills did.

Common freshwater fish that can breathe air: catfish - gar - mudfish.

There are others, but not ones caught by hook and line for the most part.

The greatest depleter of DO is rainwater as it in itself is void of DO.

Rainwater is not devoid of dissolved oxygen. In fact, it can have relatively high concentrations of dissolved oxygen. Rainwater interacts with the air, absording oxygen as it falls. The amount of oxygen absorbed depends on the water temperature, and other factors. Cold water will absorb more dissolved oxygen than warmer water - but both will hold it.

The problem with rain is that it will usually cool the hot, but still oxygenated, upper strata of a lake, and cause it to mix with the oxygen depleted lower strata. That mix will lower the average dissolved oxygen content of the lake, possibly to lethal levels. The effect is similar to throwing a aerator into a hot, nearly oxygen depleted pond. Doing so is a recipe for a fish kill.

Runoff is a different issue as it washes nutrients, among other things, into the lake that feeds the algae, which depletes even more dissolved oxygen.

And having all those dead fish in the lake weeks before didn't help. It takes a lot of oxygen to rot a fish. It takes a whole lot of oxygen to rot a whole lot of fish.

Great stuff here.

that is indeed a great post micro, thank you.

do you think the funky green color of this water is an indicator of low oxygen levels? cuz it seems every pond i fish in that has this funky green color to is, the fishing really sucks! and i was beginning to think it may be because of low oxygen.

also, not sure if i mentioned this before, but i read in the local news paper that this lake experienced an algae bloom which depleted oxygen and killed off a whole lot of shad and bluegills. that would explain it :

Thats sad

Probably that bloom didn't "just happen". There is likely a fertility (sewage, fertilizers) issue on the adjoining land. Or, it's a really shallow pond and it's an exceptionally hot year. BTW: big fish succumb to 02 depletion first. Thus it affects the mature popn of bass especially. The good news is, if this is a freak event (somehow I doubt it) then I'd keep tabs on this pond over the next few years. You may end up with a bass boom.

the city should throw an aerator in there.

http://www.pondsolutions.com/aerators.htm

around 1300$ can buy an aerator good for a 4 acre pond

how about one good for and 18 acre lake?

http://www.vertexwaterfeatures.com/advantage_aerators.php