Opened my filter and there are thousands of these creatures swimming? What are they?

[Lauriec828]

Opened my filter and there are thousands of these creatures swimming? What are they? Will they harm my koi? Never in my life have I seen this before. Thanks so much and I look forward to hearing your feedback and advice

 

[mrsclem]

mosquito larve!

 

[JamieB]

If you have any predatory fish inside, like bettas, omnivorous fish, they’ll gladly eat them. Caution, don’t overstock their tanks or the fish could eat themselves to death, had a betta that did that. Also, if your fish doesn’t eat them all quick enough, you’ll end up with mosquitoes inside. But it’s free betta food!

 

[Tula]

Uh ohhhhh Im scratching just looking at these pictures !

 

[Mmathis]

Mosquito larvae.

How is your koi doing? We never heard back from you after your initial post.

 

[j.w]

Skeeters! Fish would love to eat them up! They will thank you for the lunch!