Rich Brown Algae Bloom

O.K. I know this is not specifically tank or native fish related but considering the extensive knowledge and education on this website of my favorite fish geeks I thought I'd see if anyone tell me anything about blooms like this.

Starting last fall after I shut down my well water flow to my trout pond it developed a rich brown algae bloom that actually appears yellow in a white bucket.







A friend that identifies microorganisms for a living identified it as a form of yellow-green algae of the Ochromonas genus. Before last fall I have never observed a brown algae bloom in any of my ponds. None of my other ponds have had a bloom like this. Anyway this spring after removing the trout I drained about 99 percent of the pond (not completely as I had some fathead minnnows in the pond I didn't want to lose) and refilled with well water. Within 2 weeks the algae bloom that is rich brown in color was back.

The fish in the pond which consist of mostly male yellow perch and fathead minnows, do not seem to be bothered by the bloom although this genus has been associated with fish kills but it's not known if it the algae bloom was a factor.

Can anyone tell me anything about this brown algae bloom? Has anyone seen a brown algae bloom?

Edited by az9, 05 April 2010 - 10:31 PM.

Oh come on now. I find it hard to believe some of you fish geeks (I say this with all due respect and admiration) cannot tell me more about this. Please? The only thing I can find with an Internet search is algae that appears brown in saltwater. The friend that identified it doesn't have much to say about it.

Ive never heard of Ochromonas being bad. It's not a Cyano or a Dinoflag, and its probably good zooplanton food. Scoop up a bucket and add some Moina or Daphnia to see if they grow well in it. I had a red bloom once in a cooler I kept on my deck. It was taxonomically a green alga, but it made the water look like Red Zinger tea. Cant recall the name, but cells were round with a gelatinous coat. It appeared just that one summer and never again.

Ive never heard of Ochromonas being bad. It's not a Cyano or a Dinoflag, and its probably good zooplanton food. Scoop up a bucket and add some Moina or Daphnia to see if they grow well in it. I had a red bloom once in a cooler I kept on my deck. It was taxonomically a green alga, but it made the water look like Red Zinger tea. Cant recall the name, but cells were round with a gelatinous coat. It appeared just that one summer and never again.

Thanks for your response.

This time analysis showed the following:

Total algae density 217,200/ml. Visibility 2 ft????
The water was dominated (89%) by a golden brown algae Chrysococcus. Yours is probably Chrysococcus minutus 5-10 um diameter. Yours were mostly 7um dia. It is a small sperical cell with one flagellum a lorica (thin shell) usually made from iron or calcium. Species is hard to determine with casual observation. Literature says they commonly give the water a brown hue.

Update:

The water color is changing to a green color. Apparently the algae species composition is changing for whatever reason. I don't believe it's due to much warmer temps as predicted by my species identifier though, as temps have been pretty much stable. We recently had some thunderstorms and 2 3/4 inches of rain over a period of a couple of days. Overcast days obviously too.

Interestingly I've observed algae changes before in my other ponds after thunderstorms. I typically don't get a significant bloom in my bluegill and yellow perch production ponds until after my first spring thunderstorms. Doesn't matter how much I fertilize until I get some thunderstorms.

How big is your pond? Could it just be spring turnover?

How big is your pond? Could it just be spring turnover?

I suppose that's a possibility.


All three ponds of which two are used for producing fish and one is used to hold broodfish are about 1/10th acre and 7 to 9 feet in depth. I supposed there could be some turnover. Just before my water stratifies in all my ponds including a much bigger one at .62 acres I crank up bottom diffusers to keep them destratified during the summer.