Pond Boss Forums STOCKING A NEW POND Types of fish to choose Will grass carp eat the organic sludge?

Just a thought, was wondering if grass carp will eat the black organic sliudge on the bottom, if they eat it when it's alive. Just wondering.

I think it's safe to answer that with a big, fat "No".

I'm also going with "No".

Nothing but anaerobic bacteria eat the black muck (sludge) on the pond bottom. Not even insect larvae or other invertebrates can survive in the anoxic black muck. However some will tolerate very low dissolved oxygen. Black anaerobic, organic sediments decompose very slowly - 20 to 30 times slower than oxygenated sediments. This is why the black muck seems to hang round a long time and in reality it accumulates because it collects faster than it decomposes. There is no oxygen in the underlying black layer and air "breathers" processors cannot live in it long enough to consume it. Some processing consumers do live on/in the very top layer when it has low concentrations of dissolved oxygen.

And there you have it...

The reason that Bill Cody is the most amazing pond scientist anywhere!

So then if I were to mix it up, aeration, per se, then it will get the exygen it needs? The pond has been around about 50 years.

So all this brings up a question about tilapia. For the past several years we've been reading and hearing from experts and hobbyists about how tilapia can help clean the muck out of our ponds.

Do the tilapia actually go after the anaerobic muck, or do they do something else that helps clean it?

Thanks,
Ken

Here is a short lesson in bottom muck - "pond mucking" if you will. Dead organic materials those that are grown inside the pond (autochthonous) and outside the pond (allochthonous) mostly settle to the bottom. This layer accumulates at various rates based on the fertility of the pond and watershed. Initially these loose, unconsolidated sediments are mixed with oxygenated (DO) water. As the invertebrates and bacteria process these sediments, they consume DO. After time without some form of mechanical disturbance that renews or mixes "fresh" water into sedimented layer, the DO is exhausted or used up in the undistrubed portion. This causes processors to die or move out of the oxygenless (anoxic) portion/layer of the sediments. Decomposition in the anoxic layer then switches from aerobic (oxygenated) to anaerobic (no oxygen) biological and chemical processes.

Essentially the only decomposers or processors able to operate in anaerobic conditions are various types of anaerobic bacteria. For anaerobic bacteria to survive without oxygen, they produce extra waste materials compared to oxygen using aerobic bacteria. One of the waste materials is hydrogen sulfide which is a sulphur compound, black and smells like rotten eggs. (An egg rotting inside the shell decomposes without oxygen). Black sediments are also acidic and laced with ammonia, methane, hydrogen and various other anoxic chemicals associated with chemically reduced conditions. Once sediments turn black, they are essentually decomposing in septic conditions and at a much slower rate - a trade off for decomposing without oxygen.

The few fish that will eat organic sediments such as tilapia or gizzard shad, are eating the upper or oxygenated layer of organics not the deeper black anoxic portion. Often the sediments in the shallows or wave zone get some mechanical mixing can remain fairly well oxygenated. These are the sediments or zone the most omnivorous fish feed in. Some of the fish in the minnow family such as common carp and a few of the minnows will root through the oxygenated sediments looking for invertebrates or pieces of edible "stuff". In this process these fish incidently consume some of the organic settlings with invertebrates gleaned from the bottom.

Now, that is some quality information, wish I could just print that. Makes you think about bacteria and aeration. Makes me wonder too if over the limit of salinity in a pond/lake could pickle the naturally occurring bacteria making it less effective?

OK, I am copying this down, and will ask Mr. Cody sometime in the future if I can possibly quote any of this for our newsletter, and 2: so our lake was overrun by Gizzard Shad, I did not know they were eating the top layer of the sediment (our saving grace is our sediment is very good, 2-4" at the deepest layers of the basin, with little change over 20 years.) I thought they were just stirring it up. We have killed them now: did they do us any favors in relation to eating the sediment top layer?
The lake is very clear, like really clear over 4' clarity right now, we killed them on July 30.

This is just an uneducated PondMeister talking, but I think the extra biomass that the GShad were in the BOW (and the extra stuff that they added to the bottom of the said BOW) more than made up for any sediment that they ate.

Only a portion of the diet for gizzard shad is sometimes orgainc sediment. Typically these fish eat zooplankton and larger phytoplankton. When preferred foods become scarce the gshad reportedly resort to eating organics. At times various types algae can inhabit the upper organic layer. This is when I think gshad will eat organics on the bottom. Also phytoplankton can settle in a layer on the bottom and be consumed by the shad.

Thank you so much for that info.

Thanks for the reply Bill. That is living proof of why you get the big bucks for being the resident expert on exotic Pond Boss subjects.

Next question -- I'm not sure how much muck I've got, nor how I can measure how much I've got. I catch the majority of my catfish with bottom baits in 5 to 8 feet of water, in areas that I feel must be over a thick muck bottom. The pond is now about 17 years old, and was seriously neglected with large influxes of erosion and leaves until about 5 years ago. I usually "chum" the bottom with cut up shrimp or balls of Wonder Bread before I start fishing for catfish.

As of this afternoon, my pond was about a 15 inches below full pool, with about three feet of visibility. All I see is a mud bottom. Is there any reasonable way to measure the muck depth in the deeper areas to know if I have a possible issue with muck?

I don't aerate, but we have a lot of wind about 10 months out of the year.


Thanks,
Ken

Ken, here is a video of the Sludge Judge that Water Wizard posted.
http://www.youtube.com/watch?v=TQsvITpXav0

http://www.pondboss.com/forums/ubbthreads.php?ubb=showflat&Main=11455&Number=153092#Post153092

AP - thanks for the tip. I've actually got a brand new, still in the box, Sludge Judge upstairs in the barn. It's a long story, but my son gave it to me as a present several years ago! I'd completely forgotten that I had the thing.

Ken