Water lettuce hosting growing population of tiny black bugs; pics included

[Miga Milan]

1800 gal pond in Florida. 84F degrees. Very hot summer. My pond is 3/4 covered with water lettuce which provides needed shade to my koi fish. Water lettuce is the only plan that has it. These bugs settle between the leaves and on top. The water lettuce looks healthy otherwise. Everything else is doing well. The amount of these tiny bugs has been growing in the last 3-4 weeks.
Anyone knows what these are?
What can I do to help clearing my plants of these? or does it go away on its own?
Is it harmful to the fish or the water quality?
Pics included.
Thank you in advance for any help you may provide. Miga

 

[Meyer Jordan]

No idea what they are based on the photos, but the only thing that you can do is spray them off with the garden hose. The fish will eat them quickly.

 

[Faebinder]

This is my first year having a full set of water lettuce... I find them much more annoying compared to hyacinths and frog bits or duckweed. I wont get them next year. They get damaged by a lot of things way too easily.

 

[Mmathis]

This is my first year having a full set of water lettuce... I find them much more annoying compared to hyacinths and frog bits or duckweed. I wont get them next year. They get damaged by a lot of things way too easily.

Any suggestions regarding the bugs?

 

[Faebinder]

Any suggestions regarding the bugs?

Remove the water lettuce and add more hyacinths.

If you insist, you could remove the water lettuce to a separate tank and spray them and then wash them very well for a while. You run the risk of a little of the bug spray getting in the water when removing them from the tank back to the pond.

 

[adavisus]

Aphids drown easy, a harsh mist spray will knock their numbers down

A couple of sprays a day should see their numbers crumble

Water lettuce has raphides in its sap, not good for fish tums, at all, you might reconsider using toxic plants in large numbers, for shade...

 

[Mmathis]

Water lettuce has raphides in its sap, not good for fish tums, at all, you might reconsider using toxic plants in large numbers, for shade...

Never knew......interesting!

 

[Miga Milan]

Aphids drown easy, a harsh mist spray will knock their numbers down

A couple of sprays a day should see their numbers crumble

Water lettuce has raphides in its sap, not good for fish tums, at all, you might reconsider using toxic plants in large numbers, for shade...

Thank you, however I notice my fish do not eat or nibble at the water lettuce much at all. They are more interested in the algae that sticks to the rocks. What type of toxic plants do you suggest?

 

[Miga Milan]

Remove the water lettuce and add more hyacinths.

If you insist, you could remove the water lettuce to a separate tank and spray them and then wash them very well for a while. You run the risk of a little of the bug spray getting in the water when removing them from the tank back to the pond.

Thank you. I will try moving them to a container and hosing down. Someone suggested washing with a bit of dish soap and rinsing very well before placing back. Don't want to risk using bug spray that may hurt the fish.

 

[Miga Milan]

No idea what they are based on the photos, but the only thing that you can do is spray them off with the garden hose. The fish will eat them quickly.

TY. I will try that.

 

[Mmathis]

Thank you, however I notice my fish do not eat or nibble at the water lettuce much at all. They are more interested in the algae that sticks to the rocks. What type of toxic plants do you suggest?

I think what he meant was to reconsider the use of any toxic plant in large numbers. IOW, consider NOT using them, in this case the WL.

 

[Mmathis]

@adavisus Concerning "toxic plants" and aphids..... I think I just put 2 & 2 together regarding my swamp milkweed. I don't know what it's called, but do know that milkweed does contain a chemical considered toxic. When I find oleander aphids on mine, I'll swish the leaves in the pond for the fish to eat the aphids. So, maybe.....I shouldn't do that any more???

 

[Meyer Jordan]

I believe that what Andrew (adavisus) is referring to is calcium oxalate crystals which are rod-shaped. Other calcium oxalate crystals (druses) are star-shaped. Calcium oxalate in high enough levels is very toxic to any animal. It is contained in many leafy plants that are very nutritious such as Spinach, Swiss Chard, Rhubarb and others. In addition to Water Lettuce (Pistia), the Duckweeds also contain calcium oxalate at levels of 2 to 4 percent of weight. At these levels, considering that Duckweed has been fed to fish as a part of their diet for decades with no apparent negative effects, these levels are evidently not toxic. I would think the same would be true of Water Lettuce (Pistia).

 

[Miga Milan]

I believe that what Andrew (adavisus) is referring to is calcium oxalate crystals which are rod-shaped. Other calcium oxalate crystals (druses) are star-shaped. Calcium oxalate in high enough levels is very toxic to any animal. It is contained in many leafy plants that are very nutritious such as Spinach, Swiss Chard, Rhubarb and others. In addition to Water Lettuce (Pistia), the Duckweeds also contain calcium oxalate at levels of 2 to 4 percent of weight. At these levels, considering that Duckweed has been fed to fish as a part of their diet for decades with no apparent negative effects, these levels are evidently not toxic. I would think the same would be true of Water Lettuce (Pistia).

Thank you so much for the clarification and enlightening me on the topic. I will keep my lettuce. It's the only shade I have for my fish. They would not be happy without it down here in FL. The bugs are not harming the lettuce (visibly at least) and it has not gotten worse. Their presence is just pretty obnoxious.

 

[Miga Milan]

Update:the bugs on the water lettice have pretty much vanished. I expect they will be an unwanted seasonal visitor in my pond.