Pond Boss Forums INTRO Questions & Observations Grass Carp

OK you gurus. How much will grass carp impact filamented alge in a pond void of all other vegetation? I can't get Tilapia and chemicals are not an option. I have a HUGE amount of it and I'm worried about the D.O. levels from it decomposing if treated.

h20fwlkillr,

Not much. In my experience, they do not like algae. There is always some kind of vegetation around a pond and they will eat just about anything before algae....but if that is truely the only thing available, they may eat enough for them to sustain themselves but not make a significant dent in the stuff...thats my experience.

I second what ML says. We have them in about all lakes we manage and still battle filamentous algae most springs. They not only do not like but filamentous alge grows so quicklly they could not keep up even with really density stocking. Algaecides are cheap/effective.

Thanks for the replies. I have one more question. I have heard Israeli Carp will eat the algae almost as well as Tilapia. I can't find much info on them and was wondering if anyone here has any experience with them.

Not sure about that, but I would put Israeli carp in my pond at a LAST RESORT! They could really stir up your pond and get out of hand. BTW I think Israeli Carp is a fancy name for the common carp.

Filimentous algae is a seasonal thing in my trout pond. It's fairly excessive early in the season and then just disappears. I do net it out on a daily basis and dispose of it. At some point late in the spring I think the chara takes over and outcompetes the filimentous algae in slightly warmer water. Another factor could be I do add bacteria which can't work well until water temps get up to the mid 50's.

Have you tried bacterial augmentation? How much macrophytes (rooted vegetation) do you have? Manytimes if macrophytes or phytoplankton are scarce than filimentous algae is prolific as something has to uptake the nutrients.

Additionaly do have have excessive shallow water around the edges? If so that will contribute to the problem. Any way you can reduce nutrients going in?

Israeli carp are mirror carp(a strain of common carp with large scaleless areas on body). They eat a small amount of algae but any or almost all algae control due to them is from rooting action in sediments and stirring up mud. The "mud rooting" while looking for sediment living invertebrates produces resulting turbidity and sedimenting mud particles inhibits light peneteration and stiffles bottom plant growth.

I have 5 other ponds and this one is the only one giving me problems. It sits in a hay field that hasn't been fertilized in about 7 years. My pond is about a year old with no other vegetation besides the filamented algae. The CC keep the water very turbid, but the stuff just keeps growing at depths up to 3 feet. Visability is only about 8".
I was out of town for a week, came home and found my pond overran with it. Before that there was very little of it. With so much of it, I hate to use chemicals. I have no aeration, water temps are in the mid 80's, and the pond is in full sun in a low spot with very little wind. I'm afraid of oxygen depletion. Raking it out was a waste of time. It grew back as quick as I could rake it out. I am just trying to find a more permanent way to rid myself of it and keep it under control.

I went ahead and added the copper sulfate crystals to about 25% of the worst areas 2 days ago. It did a real nice job of killing it. After a couple of hours the algae was black. But my worst fears my be happening right before my eyes. In the time since I have had 6 floaters. 5 CC and 1 LMB. The copper sulfate may have had nothing to do with it...I just don't know. I haven't seen any fish gasping at the surface and I still see bass chasing creek chubs in the shallows. Any idea what else could be causing this???

h20fwlkillr,

I'd bet on the copper sulfate as the cause...chelated copper is the only way to go (if you use chemicals on algae) and even then there is some risk of fish kill as has been reported herein.

h20fwlkillr :

ML is correct. Copper sulfate can cause fish to be unable to uptake O2 . It is not an O2 depletion , but that in the area of treatment when the fish's gills contact to much copper sulfate in the water they can't breath . That may be why some fish were not effected. Chelated copper is much less likely to cause a problem than copper sulfate. A second way it can cause a problem but not as quickly is by O2 depletion. When the plant material dies it stops producing O2 and starts using up O2 in decomposition . ewest

If it was the fish coming in contact w/ the copper sulfate, then I should assume this will be coming to an end soon?? I took off work early and seined out all the dead algae I could. Hopefully that will help w/ the DO levels.

Of course this is hide sight but maybe you should have seined out all you could and then applied chelated copper sulfate to only about 10 percent at a time? There are also algaecides that do not have copper in them.